Bug fixes

- Add functional tests
- Fix coding standards
- Fix issue "Join WebformFieldsResource and WebformSubmissionResource into one single resource" (https://www.drupal.org/project/webform_rest/issues/3003437)
- Fix issue "RuntimeException when posting a new submission" (https://www.drupal.org/project/webform_rest/issues/3171601)

Fix scan template directory

Fixes #3111719: hook_path_insert deprecated, needs to be replaced.

Use new release name convention.

Compatibility with Drupal 9 + #3127429: access param should not be mandatory.

First testing release for 2.0.0. This release features the first of some planned code rewrites that break any other code that may depend on it. Field collection field type support has also been completely removed (it was deprecated in 8.x-1.0-rc5).