EQL: implement wildcard function

[rw-access]

Part of #51556
https://eql.readthedocs.io/en/latest/query-guide/functions.html#wildcard

Specifically, we should catch wildcard(field, "wildcard1", "wildcard2", "wildcard3", ...) and convert to Like as an optimizer rule.

Function behavior

Validation requirements:

• All wildcard parameters must be constant/foldable strings in the query
• There must be at least one wildcard string
• The first parameter must be a string but may or not be foldable.

null behavior:

• wildcard(missing/null, ...) ==> null
• wildcard(string, ...) => true or false
• wildcard(non-null, non-string) => null (if necessary)
  • this shouldn't be possible when compiling to match and using an indexed field. but can we query non-indexed fields? would a document ever have a non-string value?

[elasticmachine]

Pinging @elastic/es-search (:Search/EQL)