Add a complementary `downloadArtifact()` with remote artifact container URL method

[lbroudoux]

Reason/Context

This is required by microcks/microcks-quarkus#164

Description

As of today we have no mean to specify a RemoteArtifact (where remote url is bound to a secret) when importing a remote artifact into a started Microcks container.

Implementation ideas

We'd probably need to make downloadArtifact(String microcksContainerHttpEndpoint, RemoteArtifact remoteArtifact, boolean mainArtifact) public...