Extract a simple query language syntax from the Kuery grammar

[Bargs]

Related to #10789

Kuery is an experimental new language and a significant departure from the existing Kibana query language. Our goal was to implement a laundry list of improvements the the Kibana search experience. In hindsight, I think we unnecessarily coupled many of these improvements to the introduction of a new syntax.

In order to ship improvements more quickly, we can start by enhancing and refining the existing query language. We can implement a grammar that parses a lucene-like query syntax and begin building useful features like autocomplete on top of that simple language. To users this should feel more like an enhancement to the existing query language than a switch to an entirely new language.

The scope of this ticket only covers the plumbing necessary to extract the simple language from Kuery.