Speed up merge_tile_datasets_within_extent

[mikegraham]

Closes #147

Update merge_tile_datasets_within_extent to do the windowing at the rasterio level

[cmarshak]

Hey @mikegraham - sorry it's getting delayed. I am not going to be able to review this for a little bit (likely a couple weeks).

Hope you can use your forked version.

Also, make sure (generally) there are no breaking changes since this library is used by a few different operational libraries that rely on consistent APIs including DockerizedTopsApp with generate S1 GUNWs.

I really hate this pattern that I have from reproject_to_arr_to_match_profile:

https://github.com/ACCESS-Cloud-Based-InSAR/DockerizedTopsApp/blob/888634d7fa627fcef41f42fce5155e8ad973e94e/isce2_topsapp/localize_dem.py#L118C1-L125C50

I wish I could remove the second line e.g. if an array is passed that has shape length 2, it returns an array of similar shape, but a lot of different downstream libraries already account for this annoyance.

Anyways, thanks!