Add ES|QL (Elasticsearch Query Language) as a new data language

[bartoval]

Add ES|QL (Elasticsearch Query Language) as a new data language

Description

ES|QL is Elastic's query language for Elasticsearch, available since 8.11.0 (November 2023). It's a piped language — queries look like FROM index | WHERE ... | STATS ... | LIMIT 10 — used in .esql files for test fixtures, security detection rules, observability runbooks, and benchmark suites.

The esql alias enables syntax highlighting in fenced code blocks (```esql).

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.esql+STATS
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/elastic/rally-internal-tracks/tree/master/scale-observability/queries/esql
      • https://github.com/elastic/esql-syntax/blob/main/samples/example.esql
    • Sample license(s): Apache 2.0
  • I have included a syntax highlighting grammar: https://github.com/elastic/esql-syntax/blob/main/syntaxes/esql.tmLanguage.json
  • I have added a color
    • Hex value: #00BFB3
    • Rationale: Official Elastic brand color (teal), used across Elastic products and documentation.
  • I have updated the heuristics to distinguish my language from others using the same extension.
    The .esql extension is not currently assigned to any other language in Linguist.