Issue #3469597 by gg24, sonnykt, nadim hossain, yovince, ciprian.stavovei: Add compatiblity with Elasticsearch 8.x, #3100797 Allow alter the list of attachment, #3105993 error with cluster prefix/suffix, #3114500 Add a settings for indexed_chars.

• Issue #3469597 by gg24, sonnykt: Make search_api_elasticsearch_attachments compatible with Elasticsearch 8.x.
• Issue #3100797 by sonnykt, nadim hossain: Allow other modules to alter the list of attachment of the node to be indexed.
• Issue #3105993 by yovince, sonnykt, ciprian.stavovei: Fatal error when working with indices with custom cluster prefix/suffix
• Issue #3114500 by sonnykt: Add a settings for indexed_chars to extract more than 100K characters.