Description

This PR adds code for interfacing with Overture for building data, allowing the download of only a subset of data (constrained by a given bounding box), instead of the entire dataset for the country. The downloaded building.geoparquet file is significantly smaller as a result.

I left the original national downloader in for not, in case it's still useful.

I have not tested this yet, beyond peering inside the geoparaquet file (I run Linux, so can't run the GUI). Please could you confirm?

Some things to note:

• There are two endpoints: S3 or Azure (I arbitrarily chose S3)
• S3 region is fixed, as only us-west-2 is available
• I haven't yet figured out the version parameter, how to auto pick latest, or if that's even possible without hacking
• I'm not so familiar with the data formats, so extra optimisation is perhaps possible.

Fixes #133

Type of change

• Documentation (non-breaking change that adds or improves the documentation)
• New feature (non-breaking change which adds functionality)
• Optimization (non-breaking, back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (whatever its nature)

Key checklist

• All tests pass (eg. python -m pytest)
• The documentation builds and looks OK (eg. python -m sphinx -b html docs docs/build)
• Pre-commit hooks run successfully (eg. pre-commit run --all-files)

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added or an issue has been opened to tackle that in the future. (Indicate issue here: # (issue))