Extend Geospatial support to include additional functions like st_envelope, st_buffer etc.

[ksnijjer]

We have a geospatial usecase where we need to find the points in a polygon which Pinot can do really well with ST_Contains but what we need to do is fetch the Polygon by creating a Bounding box around a Point. Other tools for e.g postgis offers function like ST_Envelope to create this bounding box and St_Buffer to take a buffer for the radius.

Request is to add similar geometry capabilities to Pinot as well vs. having to manually define it.

cc @mayankshriv