geogfn: investigate making point intersects cheaper

[otan]

See #69762.

Points intersection could be cheaper in CRDB by comparing whether two points are equal. Currently, we use intersectscell, which allows for 1cm of error (do we want that?) but does make it slower. Changing this is a potentially backwards incompatible change, so deferring this as an issue.

Jira issue: CRDB-9938

[blathers-crl]

Hi @otan, please add a C-ategory label to your issue. Check out the label system docs.

While you're here, please consider adding an A- label to help keep our repository tidy.

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

[github-actions]

We have marked this issue as stale because it has been inactive for
18 months. If this issue is still relevant, removing the stale label
or adding a comment will keep it active. Otherwise, we'll close it in
10 days to keep the issue queue tidy. Thank you for your contribution
to CockroachDB!