fix: identical endpoint name conflicts - #1521

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In
`@controllers/controller/devworkspacerouting/devworkspacerouting_controller.go`:
- Around line 128-133: The code sets workspaceMeta.DevWorkspaceName =
instance.Name but must use the parent DevWorkspace's name from
instance.OwnerReferences; update the DevWorkspaceMetadata population so
DevWorkspaceName is assigned from the owner reference whose Kind (or
APIVersion+Kind) indicates the parent DevWorkspace (e.g., iterate
instance.OwnerReferences, find ownerRef.Kind == "DevWorkspace" and use
ownerRef.Name), and fall back to instance.Name only if no such ownerRef exists;
change the assignment near workspaceMeta (DevWorkspaceMetadata,
workspaceMeta.DevWorkspaceName) to use that ownerRef-derived name.

In `@controllers/controller/devworkspacerouting/solvers/common_test.go`:
- Around line 16-27: Reorder the import block in common_test.go into three
groups with blank lines between them: (1) standard library (e.g., "testing"),
(2) third-party and Kubernetes packages (e.g.,
"github.com/stretchr/testify/assert", "k8s.io/api/core/v1" as corev1,
"k8s.io/apimachinery/pkg/apis/meta/v1" as metav1,
"k8s.io/apimachinery/pkg/runtime",
"sigs.k8s.io/controller-runtime/pkg/client/fake",
"sigs.k8s.io/controller-runtime/pkg/log/zap"), and (3) project-local imports
(e.g., "github.com/devfile/devworkspace-operator/apis/controller/v1alpha1" as
controllerv1alpha1 and
"github.com/devfile/devworkspace-operator/pkg/constants"); insert single blank
lines between these groups and then run 'make fmt' to apply formatting.

In `@webhook/workspace/handler/validate_test.go`:
- Around line 105-124: The test currently asserts a ServiceConflictError when
validateEndpoints (on WebhookHandler) is called with a workspace and a
deletingWorkspace (created via setupWorkspace) that has DeletionTimestamp set;
update the test so it reflects webhook behavior that ignores
deletion-timestamped workspaces: call handler.validateEndpoints(context.TODO(),
workspace) and assert no error (i.e., expect nil) instead of asserting
Error/ErrorAs for *solvers.ServiceConflictError, and remove or replace the
subsequent checks for conflictErr.EndpointName/WorkspaceName accordingly so the
test verifies that deletion-timestamped workspaces do not cause conflicts.
- Around line 16-31: Reorder the import block in the validate_test.go file into
three blank-line-separated groups: (1) standard library imports (context, os,
path/filepath, testing), (2) third-party and Kubernetes imports
(github.com/stretchr/testify/assert, sigs.k8s.io/... , k8s.io/... etc.), and (3)
project-local imports (github.com/devfile/... and your controller packages),
making sure each package stays in its respective group; after rearranging, run
make fmt to apply formatting.

In `@webhook/workspace/handler/validate.go`:
- Around line 81-84: validateEndpoints currently returns raw errors from
h.Client.List which are being appended to devfileErrors and treated as user
validation failures in ValidateDevfile; change validateEndpoints signature to
return (*solvers.ServiceConflictError, error) so real validation conflicts come
back as the typed value and infrastructure/API errors flow via the error return,
update validateEndpoints to return (nil, err) for h.Client.List failures and
(conflictErr, nil) for validation failures, then in ValidateDevfile (and the
other call site around lines 109-112) check the error return first and convert
infrastructure errors into admission.Errored(http.StatusBadRequest, err) (or
propagate the error) instead of appending to devfileErrors, only append
conflictErr.Error() to devfileErrors when the typed conflict value is returned.
- Around line 114-130: The validation loop currently only skips the same
workspace by UID but still inspects workspaces that are being deleted; modify
the loop that iterates workspaceList.Items (and the check around otherWorkspace)
to also skip any otherWorkspace with a non-nil DeletionTimestamp (i.e., treat
terminating workspaces as excluded from discoverable endpoint conflict checks),
so that discoverableEndpoints lookup and potential return of
solvers.ServiceConflictError only considers non-terminating workspaces.

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@webhook/workspace/handler/validate_test.go`:
- Line 1: Update the copyright header in
webhook/workspace/handler/validate_test.go by changing the year range string "//
Copyright (c) 2019-2025 Red Hat, Inc." to the current-year range "// Copyright
(c) 2019-2026 Red Hat, Inc."; locate and replace that exact header line at the
top of the file so it matches the required format used across Go sources.
- Line 58: The test currently ignores the error from dwv2.AddToScheme(scheme);
change this to explicitly assert success by calling assert.NoError(t,
dwv2.AddToScheme(scheme)) so the scheme initialization failure surfaces in the
test; locate the call to dwv2.AddToScheme in validate_test.go (the variable
scheme) and replace the `_ =` ignoring pattern with the assert.NoError check
(using the existing testify/assert import).

In `@webhook/workspace/handler/validate.go`:
- Around line 24-29: Reorder the import block in validate.go so imports follow
Go grouping: first any standard-library packages (none shown here), then a blank
line, then third-party and Kubernetes imports together (e.g.,
"github.com/devfile/api/v2/..." packages and
"sigs.k8s.io/controller-runtime/..." client and admission), then a blank line,
and finally project-local imports (e.g.,
"github.com/devfile/devworkspace-operator/apis/controller/v1alpha1" and
"github.com/devfile/devworkspace-operator/controllers/controller/devworkspacerouting/solvers");
ensure there are blank lines separating these three groups and keep the existing
import identifiers (dwv2, devfilevalidation, v1alpha1, solvers, client,
admission) intact.