ES|QL: improve docs about escaping for GROK, DISSECT, LIKE, RLIKE

[luigidellaquila]

Escaping special characters in strings is complex.
Escaping them in regex is painful.
We can make user's life easier by suggesting to use triple quotes strings in commands and operators that will likely contain special characters (GROK, DISSECT, LIKE, RLIKE). This will significantly reduce the number of escapes needed.

eg.

ROW field = """foo [bar\\baz]""" | GROK field "foo \\[%{WORD:x}\\\\%{WORD:y}\\]"

vs

ROW field = """foo [bar\\baz]""" | GROK field """foo \[%{WORD:x}\\%{WORD:y}\]"""

or for the typical Windows paths:

| GROK field "C:\\\\my\\\\folder\\\\and\\\\%{WORD:file}\\.exe"

vs

| GROK field """C:\\my\\folder\\and\\%{WORD:file}\.exe"""

This PR enchances the docs for all the operators/commands mentioned above:

• adding triple quotes """ in all the sample queries
• explicitly mentioning escaping and suggesting to always use triple quotes

Fixes: #115051

[github-actions]

Documentation preview:

• ✨ Changed pages

[luigidellaquila]

@elasticmachine update branch

[luigidellaquila]

@elasticmachine update branch

[luigidellaquila]

@elasticmachine update branch

[elasticsearchmachine]

Pinging @elastic/es-docs (Team:Docs)

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[bpintea]

I'd only note that in some cases we only give triple quotes examples, it might be good to keep some simple ones too. But LGTM.

[luigidellaquila]

I'd only note that in some cases we only give triple quotes examples

Yeah, it's a bit extreme 😅
But the intention is to set triple quotes as a standard for regex-like strings, to avoid problems when they become more complex

[elasticsearchmachine]

💔 Backport failed

Status	Branch	Result
❌	8.15	Commit could not be cherrypicked due to conflicts
✅	8.16
✅	8.x

You can use sqren/backport to manually backport by running backport --upstream elastic/elasticsearch --pr 115320