[ES|QL] Add support for =~ operator (elastic#174732)

## Summary

Keep in sync with new ES|QL builtin function addition:
elastic/elasticsearch#103656

Do not merge until the related ER PR is still in review.

### Checklist

- [x]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

packages/kbn-monaco/src/esql/antlr/esql_lexer.g4

@@ -138,6 +138,7 @@ RP : ')';
 TRUE : T R U E;
 
 EQ  : '==';
+CIEQ : '=~';
 NEQ : '!=';
 LT  : '<';
 LTE : '<=';

packages/kbn-monaco/src/esql/antlr/esql_lexer.tokens

@@ -50,58 +50,59 @@ RLIKE=49
 RP=50
 TRUE=51
 EQ=52
-NEQ=53
-LT=54
-LTE=55
-GT=56
-GTE=57
-PLUS=58
-MINUS=59
-ASTERISK=60
-SLASH=61
-PERCENT=62
-OPENING_BRACKET=63
-CLOSING_BRACKET=64
-UNQUOTED_IDENTIFIER=65
-QUOTED_IDENTIFIER=66
-EXPR_LINE_COMMENT=67
-EXPR_MULTILINE_COMMENT=68
-EXPR_WS=69
-METADATA=70
-FROM_UNQUOTED_IDENTIFIER=71
-FROM_LINE_COMMENT=72
-FROM_MULTILINE_COMMENT=73
-FROM_WS=74
-UNQUOTED_ID_PATTERN=75
-PROJECT_LINE_COMMENT=76
-PROJECT_MULTILINE_COMMENT=77
-PROJECT_WS=78
-AS=79
-RENAME_LINE_COMMENT=80
-RENAME_MULTILINE_COMMENT=81
-RENAME_WS=82
-ON=83
-WITH=84
-ENRICH_POLICY_NAME=85
-ENRICH_LINE_COMMENT=86
-ENRICH_MULTILINE_COMMENT=87
-ENRICH_WS=88
-ENRICH_FIELD_LINE_COMMENT=89
-ENRICH_FIELD_MULTILINE_COMMENT=90
-ENRICH_FIELD_WS=91
-MVEXPAND_LINE_COMMENT=92
-MVEXPAND_MULTILINE_COMMENT=93
-MVEXPAND_WS=94
-INFO=95
-FUNCTIONS=96
-SHOW_LINE_COMMENT=97
-SHOW_MULTILINE_COMMENT=98
-SHOW_WS=99
-COLON=100
-SETTING=101
-SETTING_LINE_COMMENT=102
-SETTTING_MULTILINE_COMMENT=103
-SETTING_WS=104
+CIEQ=53
+NEQ=54
+LT=55
+LTE=56
+GT=57
+GTE=58
+PLUS=59
+MINUS=60
+ASTERISK=61
+SLASH=62
+PERCENT=63
+OPENING_BRACKET=64
+CLOSING_BRACKET=65
+UNQUOTED_IDENTIFIER=66
+QUOTED_IDENTIFIER=67
+EXPR_LINE_COMMENT=68
+EXPR_MULTILINE_COMMENT=69
+EXPR_WS=70
+METADATA=71
+FROM_UNQUOTED_IDENTIFIER=72
+FROM_LINE_COMMENT=73
+FROM_MULTILINE_COMMENT=74
+FROM_WS=75
+UNQUOTED_ID_PATTERN=76
+PROJECT_LINE_COMMENT=77
+PROJECT_MULTILINE_COMMENT=78
+PROJECT_WS=79
+AS=80
+RENAME_LINE_COMMENT=81
+RENAME_MULTILINE_COMMENT=82
+RENAME_WS=83
+ON=84
+WITH=85
+ENRICH_POLICY_NAME=86
+ENRICH_LINE_COMMENT=87
+ENRICH_MULTILINE_COMMENT=88
+ENRICH_WS=89
+ENRICH_FIELD_LINE_COMMENT=90
+ENRICH_FIELD_MULTILINE_COMMENT=91
+ENRICH_FIELD_WS=92
+MVEXPAND_LINE_COMMENT=93
+MVEXPAND_MULTILINE_COMMENT=94
+MVEXPAND_WS=95
+INFO=96
+FUNCTIONS=97
+SHOW_LINE_COMMENT=98
+SHOW_MULTILINE_COMMENT=99
+SHOW_WS=100
+COLON=101
+SETTING=102
+SETTING_LINE_COMMENT=103
+SETTTING_MULTILINE_COMMENT=104
+SETTING_WS=105
 '|'=26
 '='=33
 ','=34
@@ -110,15 +111,16 @@ SETTING_WS=104
 '?'=48
 ')'=50
 '=='=52
-'!='=53
-'<'=54
-'<='=55
-'>'=56
-'>='=57
-'+'=58
-'-'=59
-'*'=60
-'/'=61
-'%'=62
-']'=64
-':'=100
+'=~'=53
+'!='=54
+'<'=55
+'<='=56
+'>'=57
+'>='=58
+'+'=59
+'-'=60
+'*'=61
+'/'=62
+'%'=63
+']'=65
+':'=101