[ES|QL] Update function supports and improve signatures (#166282)

## Summary

Built on top of #166157

Functions in the related PR have been added at lexer level so now the
grammar supports them.
A separate task to detach function definitions from the grammar has been
logged [here](https://github.com/elastic/kibana/issues/166242).

Took also the chance here to define better signatures for functions:


![esql_new_functions](2dc710f5-26fd-41fd-b8a6-3bed48033e7d)


### Checklist

Delete any items that are not applicable to this PR.

- [x] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)
- [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

@@ -166,11 +166,17 @@ MATH_FUNCTION
     | S U B S T R I N G
     | T R I M
     | C O N C A T
+    | C O A L E S C E
+    | G R E A T E S T
+    | L E F T
+    | N O W
+    | R I G H T
     | S T A R T S UNDERSCORE W I T H
     | D A T E UNDERSCORE F O R M A T
     | D A T E UNDERSCORE T R U N C
     | D A T E UNDERSCORE P A R S E
     | A U T O UNDERSCORE B U C K E T
+    | D A T E UNDERSCORE E X T R A C T
     | I S UNDERSCORE F I N I T E
     | I S UNDERSCORE I N F I N I T E
     | C A S E
@@ -194,10 +200,12 @@ MATH_FUNCTION
     | T O UNDERSCORE D T
     | T O UNDERSCORE D B L
     | T O UNDERSCORE D O U B L E
+    | T O UNDERSCORE D E G R E E S
     | T O UNDERSCORE I N T
     | T O UNDERSCORE I N T E G E R
-    | T O UNDERSCORE L O N G
     | T O UNDERSCORE I P
+    | T O UNDERSCORE L O N G
+    | T O UNDERSCORE R A D I A N S
     | T O UNDERSCORE V E R S I O N
     | T O UNDERSCORE U N S I G N E D UNDERSCORE L O N G
     ;
@@ -212,6 +220,20 @@ UNARY_FUNCTION
     | P E R C E N T I L E
     | M E D I A N
     | M E D I A N UNDERSCORE A B S O L U T E UNDERSCORE D E V I A T I O N
+    | A C O S
+    | A S I N
+    | A T A N
+    | A T A N '2'
+    | C E I L
+    | C O S
+    | C O S H
+    | F L O O R
+    | L T R I M
+    | S I N
+    | S I N H
+    | S Q R T
+    | T A N
+    | T A N H
     ;
 
 WHERE_FUNCTIONS

packages/kbn-monaco/src/esql/lib/autocomplete/autocomplete_definitions/utils.ts

@@ -16,6 +16,48 @@ const examplesLabel = i18n.translate('monaco.esql.autocomplete.examplesLabel', {
   defaultMessage: 'Examples:',
 });
 
+/** @internal */
+export const buildFunctionDocumentation = (
+  signatures: Array<{
+    declaration: string;
+    examples?: string[];
+  }>
+) => `
+---
+\
+***${declarationLabel}***
+${signatures
+  .map(
+    ({ declaration }) => `
+\
+  - \`\`${declaration}\`\`
+\
+`
+  )
+  .join('\n\n')}
+---
+${
+  signatures.some((examples) => examples)
+    ? `\
+***${examplesLabel}***
+\
+${signatures
+  .filter(({ examples }) => examples)
+  .map(
+    ({ examples }) => `
+  ${examples!
+    .map(
+      (i) => `
+  - \`\`${i}\`\`)
+`
+    )
+    .join('')}
+  
+`
+  )}`
+    : ''
+}`;
+
 /** @internal **/
 export const buildDocumentation = (declaration: string, examples?: string[]) => `
 ---

packages/kbn-monaco/src/esql/lib/autocomplete/autocomplete_listener.test.ts

@@ -14,6 +14,7 @@ import { getParser, ROOT_STATEMENT } from '../antlr_facade';
 
 import { isDynamicAutocompleteItem } from './dymanic_item';
 import { getDurationItemsWithQuantifier } from './helpers';
+import { mathCommandDefinition } from './autocomplete_definitions/functions_commands';
 
 describe('autocomplete_listener', () => {
   const getAutocompleteSuggestions = (text: string) => {
@@ -177,34 +178,7 @@ describe('autocomplete_listener', () => {
   });
 
   describe('eval', () => {
-    const functionSuggestions = [
+    const functionSuggestions = mathCommandDefinition.map(({ label }) => String(label));
-      'round',
-      'abs',
-      'pow',
-      'log10',
-      'concat',
-      'substring',
-      'trim',
-      'starts_with',
-      'split',
-      'to_string',
-      'to_boolean',
-      'to_datetime',
-      'to_double',
-      'to_integer',
-      'to_long',
-      'to_unsigned_long',
-      'to_ip',
-      'to_version',
-      'date_format',
-      'date_trunc',
-      'date_parse',
-      'auto_bucket',
-      'is_finite',
-      'is_infinite',
-      'case',
-      'length',
-    ];
 
     testSuggestions('from a | eval ', ['var0']);
     testSuggestions('from a | eval a ', ['=']);