builtins: implement ST_Boundary, ST_Difference, and ST_Relate with BNR

[erikgrinaker]

Release note (sql change): Implement the geometry builtins
ST_Boundary, ST_Difference, and ST_Relate (BNR variant).

Closes #48888.
Closes #48917.
Closes #49013.

[blathers-crl]

Thank you for contributing to CockroachDB. Please ensure you have followed the guidelines for creating a PR.

My owl senses detect your PR is good for review. Please keep an eye out for any test failures in CI.

I have added a few people who may be able to assist in reviewing:

• @otan (author of geo/geomfn: implement ST_Boundary({geometry}) #48888, author of geo/geomfn: implement ST_Difference({geometry,geometry}) #48917, author of geo/geomfn: implement ST_Relate({geometry,geometry,int4}) #49013)

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is otan.}

[cockroach-teamcity]

This change is 

[otan]

thank you so much!
hopefully this doesn't merge conflict...
bors r+

[craig]

Build failed (retrying...):

• GitHub CI (Cockroach)

[craig]

Build succeeded:

• GitHub CI (Cockroach)