feat: add extraMounts and volumes to migrate job

[wenzel-felix]

This PR adds the extraVolumes and extraVolumeMounts to the migration job.

Description

As this PR (#142) also already did, I added extraVolumes and extraVolumeMounts to the migrate job allowing for different scenarios not possible without, eg. mounting CA bundles or mounting secrets via SPC for the database credentials to be used by the job.

Compared to the other PR I also added the default values in the values.yaml and added the new values to the validation schema.

References

#142

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

[linux-foundation-easycla]

• ✅login: wenzel-felix / (71ac6e3)
• ✅login: wenzel-felix / (71ac6e3, ba12425)

The committers listed above are authorized under a signed CLA.

[wenzel-felix]

Hi @rhamzeh / @jon-whit , sorry for asking again, but could you review the changes?
These are very minor additions to the migration hook job.

[rhamzeh]

Thanks for your PR @wenzel-felix - apologies for the delay in the review!