TPT-4256: Implemented changes for SLADE and CLEO projects

[ezilber-akamai]

📝 Description

Added new kernel and boot_size fields to Linode Create options. Also added a notice that one of root_pass authorized_users, or authorized_keys is required when image is provided rather than just requiring root_pass.

✔️ How to Test

make test-unit

[Copilot]

Pull request overview

This PR updates the Linode instance/disk create request models to support new SLADE/CLEO-related fields and to allow omitting root_pass by switching it to a pointer type.

Changes:

• Add kernel and boot_size to InstanceCreateOptions.
• Change root_pass from string to *string for Instance create/rebuild and Disk create options (breaking change).
• Update unit/integration tests to use linodego.Pointer(...) for the new pointer-based RootPass fields.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
instances.go	Makes RootPass optional via *string; adds Kernel and BootSize to instance create options.
instance_disks.go	Makes disk-create RootPass optional via *string.
test/unit/instance_test.go	Updates unit tests for instance create/rebuild to use pointer-based RootPass; adds coverage for new fields in the options struct.
test/unit/instance_disks_test.go	Updates unit test for disk create to use pointer-based RootPass.
test/integration/instances_test.go	Updates integration tests to use pointer-based RootPass in instance/disk workflows.
test/integration/instance_reserved_ips_test.go	Updates integration tests to use pointer-based RootPass when creating instances.
test/integration/instance_interfaces_test.go	Updates integration helper to use pointer-based RootPass.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[zliang-akamai]

Looks good to me, nice work!