[ES|QL] Integration tests (elastic#177017)

## Summary

The validation test suite now dumps all test cases into a JSON with a
flag that tell if the query should fail or not.

On top of that an integration test has been written, who collects the
JSON and execute it again against the ES ES|QL `_query` endpoint, then
compare the two result.

* if both results are the same (both pass or errors) then it's good to
go ✅
* if client side fails and ES pass, then it's a failure ❌ 
* if client side passes and ES fails, then it's bad but still ok ⚠️ 
* in this case the error is logged and stored into a JSON (not
committed)

All tests are ran 8 times ( stringField => `["text", "keyword"]`,
numberField => `["integer", "double", "long", "unsigned_long]` for a
totale of ~16k assertions (2000 x 8 tests).
Assertions have to be within a single test to avoid memory issues on the
CI otherwise.

~~Fixes the signature utility for functions with a minimum number of
args.~~



### Checklist

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

Co-authored-by: kibanamachine <[email protected]>
Co-authored-by: Stratoula Kalafateli <[email protected]>

packages/kbn-monaco/src/esql/lib/ast/validation/.gitignore

@@ -0,0 +1 @@
+esql_validation_missmatches.json