Support geohash, geotile and geohex grid types

[craigtaverner]

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.

One of the main goals of this work was to also support the concept of a geogrid search. This means "find all documents that intersect a grid cell", similar to the Query DSL version. This is achieved by enabling the use of these three new types in the ST_INTERSECTS function, so a query like this would satisfy the requirement:

FROM airports
| WHERE ST_INTERSECTS(location, "3/4/3"::geotile)

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[elasticsearchmachine]

Hi @craigtaverner, I've created a changelog YAML for you.