fix(package-mode): scoped registry manifest conditional

[nvandessel]

Changes

• fixes the bug introduced in Feature: Support Package Testing for Packages with Dependencies Outside of the Unity Registry #225 where an empty scoped registry is added to the manifest.json even when it is not supplied
• adds a conditional check to the jq argument that modifies the manifest.json to only include add the scoped registry when both the URL and Scopes are supplied.

Related Issues

• N/A

Related PRs

• N/A

Successful Workflow Run Link

PRs don't have access to secrets so you will need to provide a link to a successful run
of the workflows from your own repo.

• https://github.com/luminopia/unity-test-runner/actions/runs/8285355477
• worth noting that while one of the tests failed in this run, it did correctly resolve the dependencies, however it encountered a license collision due to me not being able to acquire a personal license to test with.

Checklist

• Read the contribution guide and accept the code of conduct
• Docs (If new inputs or outputs have been added or changes to behavior that should be documented. Please make a PR
  in the documentation repo)
• Readme (updated or not needed)
• Tests (added, updated or not needed)

[github-actions]

[GabLeRoux]

Fixes this:

Failed to resolve packages: Registry configuration is invalid:
  Scoped registry at position 1 is invalid:
    "scopedRegistries[0].url" is not allowed to be empty
    "scopedRegistries[0].scopes[0]" is not allowed to be empty. No packages loaded.
./External/baselib/builds/Include/Internal/../C/Internal/Baselib_Semaphore_FutexBased.inl.h(158): Assertion failed (count >= 0) - Destruction is not allowed when there are still threads waiting on the semaphore.
Unexpected exit code 133