Make DevelController more data source agnostic

Setup

Most likely irrelevant for this issue, but here we go:

• Solr version: 8.11.2
• Drupal Core version: cross site index, some 9.5.11, some 10.0.11
• Search API version: patched 1.x-dev
• Search API Solr version: patched 4.3.0
• Configured Solr Connector: Standard

Issue

The way \Drupal\search_api_solr_devel\Controller\DevelController checks whether the datasource indexes an entity type, and the way it generates item ids, it basically only works with the default data sources or if you carefully choose your datasource plugin id and use the same ids. This could leverage more of the API to be a little bit more agnostic about the data sources in use.

Proposed resolution

Ask the datasource what entity type it wants to provide data for and to generate the item id for the entity.

STR

Write your own datasource that doesn't use ":entity_type_id" as suffix of the plugin id and/or uses different syntax for the item ids than "entity id:language id". The controller could provide data for these as well, but it doesn't.