Introduce strategy or query for exact querying of text fields

[costin]

In languages implemented on top of Elasticsearch, exact matching on text field (non-exact fields) is problematic since the match can happen in a non exact fashion (e.g. a text field with value "an apple" can match "apple").

Examples of said discussions are mentioned are #52709 and a strategy for coping with this (falling back to keyword for aggregations and exact comparisons, in SQL, is documented here.

As different languages across the stack (KQL, EQL, SQL) have to deal with this issue, it's worth investigating whether having a generalized approach or even better, support for said strategy in Elasticsearch itself is desirable.

[elasticmachine]

Pinging @elastic/es-search (:Search/Search)

[mayya-sharipova]

We had a discussion within the search team, and have decided the following:

• Use term-based queries for exact match for the keyword family.
• We are going to add multi-fields info into the fields caps. This should help to forward exact match queries to specific field types.

I am closing this issue as we don't plan to introduce any generalized approach on ES side. There will NO be special exact_match query. Please reopen if there is a plan to do something general for query languages.