Remove dangerous enforced depencies of config entities on islandora_core_feature.

[rosiel]

What does this Pull Request do?

Removes unnecessary 'enforced' dependencies, particularly on the islandora core feature. This was identified as something we should do during the Starter Site creation.

Related GitHub Issue

• [TECH DEBT] Some configs are enforced to depend on "Islandora Core Feature" #8

What's new?

• In the unlikely event you need to uninstall the islandora core module (or other islandora modules), don't delete all your content and break the site beyond further use.
• This is a niche use case but would make development easier.
• This follows the Features use pattern of "install the Feature, import the config, then uninstall the Feature and go your own way."
• It does not preclude the Features pattern of "install the Feature, import the config, and leave the feature enabled so it can detect and import new changes". (though I'm not sure we're really using this to any degree?)
• Note that lots of configs here already rely on certain modules (in the computed modules: key), so will be uninstalled automatically, even after this PR. I'm just removing "islandora_core_feature" across the board to be clean.
• Does this change add any new dependencies? no!
• Does this change require any other modifications to be made to the repository
  (i.e. Regeneration activity, etc.)? no!
• Could this change impact execution of existing code? no!

How should this be tested?

Recreate the issue:

• Install a site. Add some content.
• Uninstall the Islandora module.
• Try to create media content.
• Cry.

With this:

• After uninstalling, when creating Media, you should get complaints that the flysystem adapter is not found (because we hijacked all the media storage fields, so you have to reset them. 🤷 )
• But after that you can still use your site. We haven't uninstalled a bunch of core things.

Documentation Status

• Does this change existing behaviour that's currently documented?
• Does this change require new pages or sections of documentation?
• Who does this need to be documented for?
• Associated documentation pull request(s): ___ or documentation issue ___

Additional Notes:

Any additional information that you think would be helpful when reviewing this
PR.

Interested parties

Tag (@ mention) interested parties or, if unsure, @Islandora/committers

[rosiel]

Closing; superseded by #39