[ES|QL][Meta] Keep in sync with ES

[dej611]

Describe the feature:

Ideally we would like to automate most of the tasks to keep in sync the ES|QL grammar/functions/documentation/anything possible with the ES repo, and use it as "source of truth":

• [ES|QL] generate function definitions from ES metadata #179634
• Make sure any new ES|QL function comes correctly annotated (add test on ES side)
• grab the documentation from ES repo as asciidoc and translate it to markdown
  • write it into the documentation file => [ES|QL] Automatic creation of inline documentation #173492
• copy the ES|QL grammar and compile it in Kibana
  • this requires the ANTLR4 dependency to be changed: [SharedUX] Replace antlr4ts dependency with official antlr package #172199
  • run all tests
• [ES|QL] automate Elasticsearch grammar sync with a buildkite pipeline #178262

Ideally all this should happen on a daily basis and if anything changes then a new PR should be created.

[elasticmachine]

Pinging @elastic/kibana-visualizations (Team:Visualizations)

[dej611]

atm function metadata is incomplete, so we need to work together with the ES team to close this gap

Solved for aggregation and other scalar/multi-value functions via elastic/elasticsearch#103686

Make sure any new ES|QL function comes correctly annotated (add test on ES side)

Solved with elastic/elasticsearch#104249

[drewdaemon]

copy the ES|QL grammar and compile it in Kibana

Done in #178257

[elasticmachine]

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