Automatically initialize Apptainer

[natefoo]

Ultimately the goal here is to support easier production deployments where Galaxy itself does not have to be installed in the shared FS. Admins can configure the tool_dependency_dir to be on the shared FS and then we can just use Apptainer + a galaxy-job-execution container for running set_meta().

I should probably add a few more tests but wanted to get this out here for comment in case people don't like the direction I've taken.

How to test the changes?

(Select all options that apply)

• I've included I will include appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. Configure some resolvers in container_resolvers where s/singularity/apptainer/
  2. Set auto_init: true
  3. Try setting prefix and/or exec to change where Apptainer is installed.

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[natefoo]

I added some unit tests, I am a little iffy on adding to the integration tests since they are a good bit slower and our tests are already slow enough. Since the Apptainer resolvers are just the Singularity resolvers in a trenchcoat we wouldn't be testing anything new. I can add a test of the auto-init functionality though if we want.