[ES|QL][Meta] Stability improvements

[drewdaemon]

A collection of efforts to improve the stability and quality of the validation and autocomplete. This includes

• making fewer wrong suggestions
• staying better in-sync with Elasticsearch
• fewer validation false positives and false negatives
• more understandable code
• more protection from regressions

Basically, anything we can do to sleep better at night.

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• Stronger typing for function signatures (e.g. return types, parameter types are both string — they could be strongly typed and tied to the AST) [ES|QL] add typing for function parameters and return #182885
• Stronger typing for error message IDs
• Test for fewer parameters than required when minParams is defined on a function signature
• Add test coverage for packages/kbn-esql-ast — make sure we build our AST consistently and deterministically — started in [ES|QL] Adds METRICS source command AST node support in parsing #184494
• [ES|QL] add higher-level tests for the editor #180502
• [ES|QL][Meta] Keep in sync with ES #173817
• Add visual testing for the editor (could have caught [ES|QL] Multiline query in expanded mode shows undefined #180570)

[elasticmachine]

Pinging @elastic/kibana-esql (Team:ESQL)