[ES|QL] better inline casting validation with ES metadata

[drewdaemon]

What isn't currently validated

In #185904, we added basic support for validating inline casts (::).

There are a couple things we couldn't validate at the time

Type list

We don't know what types and abbreviations are valid. For example, integer is acceptable, but so is int. We took the approach of not validating the type.

Value types

Another thing we aren't able to validate is the type of the value being casted against the cast type.

For example, stringField::cartesian_point is valid but numberField::cartesian_point is not.

The reason for this is that field::cartesian_point is actually syntactic sugar for to_cartesianpoint(field). So, the inline cast value is subject to the constraints of to_cartesianpoint's call signature.

Plan

With elastic/elasticsearch#109713, Elasticsearch is providing us a cast-type-to-cast-function map which will allow us to reliably validate both of the above.

[elasticmachine]

Pinging @elastic/kibana-esql (Team:ESQL)