Add geography data type support

[cavallium]

Feature Request

Add geography data type support

Describe the solution you'd like

"geography" data type can already be encoded to / decoded from the same Geometry abstract class as "geometry".
I tried copying the geometry codec and renaming it, and it worked.

Teachability, Documentation, Adoption, Migration Strategy

The new codec can be included inside BuiltinDynamicCodecs as the geometry one.

[mp911de]

Do you want to submit a pull request?

[cavallium]

I would rather not, because I just started learning postgresql and r2dbc, I don't think I have the required skills to implement it correctly

[mdedetrich]

I have created a PR at #727