The purpose of this issue is track the progress of the is_write_index flag on aliases.

origin story: #30061

Documentation: https://www.elastic.co/guide/en/elasticsearch/reference/master/indices-aliases.html#aliases-write-index

TODO

• add is_write_index to metadata add is-write-index flag to aliases #30942
• bugfix: PUT alias api did not support is_write_index parsing add support for is_write_index in put-alias body parsing #31674
• leverage write indices for indexing/updating/deleting: add support for write index resolution when creating/updating documents #31520
• resolve how to handle alias routing values when alias points to multiple indices Metadata cannot reject aliases pointing to multiple indices when resolving routing #31936
• Update Rollover to swap is_write_index true toggles when rolling over, instead of removing alias (update rollover to leverage write-alias semantics #32216)