SQL: add multivalue field support (arrays)

[bpintea]

This is a meta issue for tracking multivalue support in SQL (arrays). The work should cover the following fields:

• core support, extraction: SQL: Introduce core support for multivalue fields #67883
• CSV, TSV, TXT support: SQL: Add text formatting support for multivalue #68606
• clients support (xDBC, CLI), BWC, QA tests: SQL: Add xDBC and CLI support. QA CSV specs #68966
• adapt to new fields-API: SQL: Update branch to include the fields API master changes #68831
• multivalue filtering
• documentation

[elasticmachine]

Pinging @elastic/es-ql (Team:QL)

[luoyuctl]

Is this feature will be support in version 8.0.0?

[FreCap]

I second @luoyuctl that this is a really important feature, also for people evaluating other sql solutions.

E.g. opendistro-sql supports this pretty well
https://github.com/opendistro-for-elasticsearch/sql

It'd be great seeing this SQL plugin have a nice support for nested docs visualization