geo: simplify WKT conversion

[otan]

Avoid the geom.T -> WKB -> geom.T hop to convert WKT. This was a relic
of using GEOS.

Release justification: risk free performance improvement
Release note (performance improvement): WKT conversion to a spatial type
is slightly improved.

[cockroach-teamcity]

This change is 

[jievince]

LGTM

[jievince]

Hi @otan, I wonder why when converting a ewkb to a geom.T, you just call the function ewkb.Unmarshal that provided by the library go-geom, but when converting a ewkt to a geom.T, you call the function wkt.Unmarshal which implemented by cockroach instead of the one that provided by go-geom?

[otan]

we ported the wkt library for go-geom as it was written against CRDB first, we just haven't ported to use that yet. you can do that if you want!

[sumeerbhola]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @otan)

[jievince]

we ported the wkt library for go-geom as it was written against CRDB first, we just haven't ported to use that yet. you can do that if you want!

Got it.

[otan]

bors r=sumeerbhola

[craig]

Build succeeded:

• GitHub CI (Cockroach)

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