Enhance CHM interpolation with optional valid region and edge cleaning

[maawoo]

This adds two additional parameters to calculate_chm:

• interp_valid_region: If True, calculates a valid region mask before interpolating.
• interp_clean_edges: If True, performs additional edge cleaning after interpolation.

Example of how it currently looks without / with interpolation:

calculate_chm(arrays[0], (1,1,1), interpolation=None)

calculate_chm(arrays[0], (1,1,1), interpolation='linear')

Improvements to interpolation logic introduced in this PR:

calculate_chm(arrays[0], (1,1,1), interpolation='linear', interp_valid_region=True)

calculate_chm(arrays[0], (1,1,1), interpolation='linear', interp_valid_region=True, interp_clean_edges=True)

I currently don't have much time to test this with other data and also to add tests. But I thought it's a good idea to already leave it here as a PR 🙂

[iosefa]

@maawoo thank you very much for the PR! I apologize it took so long for me to get to it. This looks great 🙏🏽 🚀 I will merge now. Thanks

[codecov-commenter]

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Attention: Patch coverage is 51.61290% with 15 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
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