ESQL: Un-snapshot all 3 URL scalar functions. (#135272)

* ESQL: Un-snapshot all 3 URL scalar functions: url_encode, url_encode_component, and url_decode.
- Move the declaration to be alongside string functions in the registry.
- Remove the snapshot instruction in all 3 capabilities.
- Annotate with GA/9.2.0 and run unit tests so changes trickle down to md and json files.
- Include the functions in the docs
- Add Wikipedia reference to percent-encoding, which also includes information about RFC 3986 and its unreserved chars

Resolves #134087

Author: mouhc1ne

docs/reference/query-languages/esql/_snippets/functions/description/url_encode.md

@@ -25,3 +25,6 @@
 * [`TO_LOWER`](../../functions-operators/string-functions.md#esql-to_lower)
 * [`TO_UPPER`](../../functions-operators/string-functions.md#esql-to_upper)
 * [`TRIM`](../../functions-operators/string-functions.md#esql-trim)
+* [`URL_ENCODE`](../../functions-operators/string-functions.md#esql-url_encode)
+* [`URL_ENCODE_COMPONENT`](../../functions-operators/string-functions.md#esql-url_encode_component)
+* [`URL_DECODE`](../../functions-operators/string-functions.md#esql-url_decode)

docs/reference/query-languages/esql/_snippets/functions/description/url_encode_component.md

@@ -96,3 +96,12 @@ mapped_pages:
 :::{include} ../_snippets/functions/layout/trim.md
 :::
 
+:::{include} ../_snippets/functions/layout/url_encode.md
+:::
+
+:::{include} ../_snippets/functions/layout/url_encode_component.md
+:::
+
+:::{include} ../_snippets/functions/layout/url_decode.md
+:::
+