ESQL: Add url_encode function

- Remove url_encode from docs since it's a snapshot function
- Declare it along other snapshot functions in EsqlFunctionRegistry

Author: mouhc1ne

docs/reference/query-languages/esql/_snippets/lists/string-functions.md

@@ -25,4 +25,3 @@
 * [`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)

docs/reference/query-languages/esql/functions-operators/string-functions.md

@@ -93,6 +93,3 @@ mapped_pages:
 :::{include} ../_snippets/functions/layout/trim.md
 :::
 
-:::{include} ../_snippets/functions/layout/url_encode.md
-:::
-

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/EsqlFunctionRegistry.java

@@ -449,8 +449,7 @@ private static FunctionDefinition[][] functions() {
                 def(ToString.class, ToString::new, "to_string", "to_str"),
                 def(ToTimeDuration.class, ToTimeDuration::new, "to_timeduration"),
                 def(ToUnsignedLong.class, ToUnsignedLong::new, "to_unsigned_long", "to_ulong", "to_ul"),
-                def(ToVersion.class, ToVersion::new, "to_version", "to_ver"),
-                def(UrlEncode.class, UrlEncode::new, "url_encode"), },
+                def(ToVersion.class, ToVersion::new, "to_version", "to_ver"), },
             // multivalue functions
             new FunctionDefinition[] {
                 def(MvAppend.class, MvAppend::new, "mv_append"),
@@ -515,7 +514,8 @@ private static FunctionDefinition[][] snapshotFunctions() {
                 def(L1Norm.class, L1Norm::new, "v_l1_norm"),
                 def(L2Norm.class, L2Norm::new, "v_l2_norm"),
                 def(Magnitude.class, Magnitude::new, "v_magnitude"),
-                def(Hamming.class, Hamming::new, "v_hamming") } };
+                def(Hamming.class, Hamming::new, "v_hamming"),
+                def(UrlEncode.class, UrlEncode::new, "url_encode") } };
     }
 
     public EsqlFunctionRegistry snapshotRegistry() {