[ESQL] Sort results by a date nanos field

[not-napoleon]

Description

Once we are able to load date nanos into ESQL (see #109987), the next step is sorting on those fields. This should be relatively easy as they are just signed longs under the hood, and we already support sorting by signed longs. I expect most of the work here will be writing tests.

[elasticsearchmachine]

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

[felixbarny]

Based on #111691, it sounds like this is already supported. Can this issue be closed or is there more work to do?

[not-napoleon]

This is supported and well enough tested in the CSV tests.