Add support for date_recur to unified_date

Not yet but it does not look like it'd be too difficult.

You could add a new chunk of code repeating the date range types like https://git.drupalcode.org/project/unified_date/-/blob/1.x/src/UnifiedDa... but instead the field type being date_recur.

The pattern is field_name:property_name. If property name is blank it searches value property. At a glance here https://git.drupalcode.org/project/date_recur/-/blob/3.5.x/src/Plugin/Fi... looks like you'll need ':start_date' and ':end_date'.

Beyond that assuming the module saves the entity in a normal drupal way when it recurs it should update the unified_date fine.

We should also add tests to the test sub-module (ie, add date_recur to that module info yml, copy in some example field config, add a test).

Attempt at a unifed_date_date_recur submodule