[JENKINS-56774] Add JCasC support

[basil]

See JENKINS-56774. Completes the work started in #44:

• Converts all usages of deprecated functionality in production and test code to use the non-deprecated equivalents being introduced in this PR.
• Adds a new @LocalData-based test to test the migration of the per-project datastructure from a map to two sets.
• The new test showed that the original change was incorrectly using short names rather than FQCNs for enabledStrategies and disabledStrategies. Adapted the examples in the test suite accordingly.
• Generated XML files for the old style configuration in the UI with the old version of the plugin, then applied each of the YAML files from the test suite and verified manually that the resulting XML correct.
• Configured a bunch of settings in the UI with the old version of this plugin, then did a JCasC export with these changes and verified that the result looked correct.
• Tested end-to-end with Job DSL Groovy Sandboxing.

[basil]

From my perspective, this is ready for merge and release.

[MarkEWaite]

Thanks!