Move core arrays and builders into geoarrow-array subcrate?

[kylebarron]

There's too much complexity in geoarrow-rs and it's making it hard to make progress.

I think a great way forward might be to identify pieces of geoarrow that are stable enough to be their own sub-crate and manage that refactor. E.g. in #1015 we added a geoarrow-schema crate, because the core types should be stable enough to be in a standalone crate.

I think the core array types and builders are (relatively) stable (not the indexed arrays, not the chunked arrays). Maybe those core array types should go into a geoarrow-array to mimic arrow-array?