Upgrade path for full_date data type

Here's a patch for the changes proposed above. This works with both the local elastic search instance and an ElasticCloud instance using the patch here: https://www.drupal.org/project/elasticsearch_connector/issues/3522107#co... ✨ Connect to an Elastic Cloud Hosted Deployment acting as a Search API Server by entering a Cloud ID and API key Active

Thanks for working on this! Now that we have almost 1000 installs on 8.x branch, I'd be a little cautious to add a new update hook. The issue summary suggest adding it to existing one, so it would work for people coming from 8.x-7.x branch. People already on 8.x branch have probably done this by custom module.

Also the new full_date plugin does not have same logic as 8.x-7.x branch (see https://git.drupalcode.org/project/elasticsearch_connector/-/commit/b4f2...).

We should add tests for this feature.