Support geohash, geotile and geohex grid types (#129581)

The PR at #125143 added support for `ST_GEOHASH`, `ST_GEOTILE` and `ST_GEOHEX`. However, since it used `long` as the internal type for the grid id, there was need for many additional functions for converting the `long` to and from `keyword` as well as generating `geo_shape` cell bounds for map display. Each pf these involved many more files (for the functions, their docs and the generated evaluators). With inspiration from PostGIS we decided to take a different direction, and instead use a new internal type for each grid:
* `geohash` for the `ST_GEOHASH` function, created from literal using either `TO_GEOHASH(hash)` or `hash::geohash`
* `geotile` for the `ST_GEOTILE` function, created from literal using either `TO_GEOTILE(tile)` or `tile::geotile`
* `geohex` for the `ST_GEOHEX` function, created from literal using either `TO_GEOHEX(h3)` or `h3::geohex`

This also leads to much stricter type checking as we can no longer use the `long` as a plain `long` in all functions that accept longs, or inadvertently using a geohash in a geotile function. However, the addition of new types involves a lot of boilerplate, especially considering the large number of functions that operate on all types, and need to be informed of the existence of these three new types.

Author: craigtaverner

docs/changelog/129581.yaml

@@ -0,0 +1,5 @@
+pr: 129581
+summary: "Support geohash, geotile and geohex grid types"
+area: "ES|QL"
+type: enhancement
+issues: []

docs/redirects.yml

@@ -1,7 +1,7 @@
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   'reference/query-languages/eql/eql-ex-threat-detection.md': 'docs-content://explore-analyze/query-filter/languages/example-detect-threats-with-eql.md'
-  
+
   # https://github.com/elastic/elasticsearch/pull/131385
   'reference/elasticsearch/rest-apis/retrievers.md':
     to: 'reference/elasticsearch/rest-apis/retrievers.md'
@@ -23,7 +23,7 @@ redirects:
         anchors: {'rule-retriever'}
       - to: 'reference/elasticsearch/rest-apis/retrievers/pinned-retriever.md'
         anchors: {'pinned-retriever'}
-  
+
   # ESQL command redirects - split from aggregate pages to individual pages
   'reference/query-languages/esql/commands/source-commands.md':
     to: 'reference/query-languages/esql/commands/source-commands.md'
@@ -35,7 +35,7 @@ redirects:
         anchors: {'esql-row'}
       - to: 'reference/query-languages/esql/commands/show.md'
         anchors: {'esql-show'}
-  
+
   # Handle old anchor references to esql-commands.md
   'reference/query-languages/esql/esql-commands.md':
     to: 'reference/query-languages/esql/esql-commands.md'
@@ -45,7 +45,7 @@ redirects:
         anchors: {'esql-source-commands'}
       - to: 'reference/query-languages/esql/commands/processing-commands.md'
         anchors: {'esql-processing-commands'}
-  
+
   'reference/query-languages/esql/commands/processing-commands.md':
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     anchors: {} # pass-through unlisted anchors in the `many` ruleset
@@ -98,3 +98,53 @@ redirects:
         anchors: {'query-rescorer'}
       - to: 'reference/elasticsearch/rest-apis/rescore-search-results.md'
         anchors: {'multiple-rescores'}
+
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+  'docs/reference/query-languages/esql/_snippets/functions/description/st_geotile_to_string.md': 'reference/query-languages/esql/esql-functions-operators.md'
+  'docs/reference/query-languages/esql/_snippets/functions/description/st_geohex_to_string.md': 'reference/query-languages/esql/esql-functions-operators.md'
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+  'docs/reference/query-languages/esql/_snippets/functions/description/st_geohex_to_long.md': 'reference/query-languages/esql/esql-functions-operators.md'
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