Whitelist for ConfigEntityListBuilder

Created a new MR that takes a different approach. Instead of adding support for whitelisting specific form IDs, MR !9 updates the existing ReadOnlyFormSubscriber to support automatically allowing ConfigEntityListBuilder forms to not be read-only if their corresponding entity type is whitelisted. i.e. This prevents the block_admin_display_form created by the BlockListBuilder class (which extends ConfigEntityListBuilder) if the block.block.* pattern is whitelisted.

The MR also adds a new test for this.

Attaching the diff from the MR as a patch to trigger automated testing. Also attaching a tests-only patch which should fail.

Fixed the test in the MR (forgot to turn on read-only setting in the new test). Attaching updated patches for automated testing.

Fix test in MR (for real this time). Had forgotten to add block module to list of modules for the test.

Attaching updated patches for automated testing.