move regionmaskcompat to core

[mathause]

• Somewhat part of rename and move data maniplation functions #237
• Tests added
• Passes isort . && black . && flake8
• Fully documented, including CHANGELOG.rst

Moves regionmask.py to core to mark that we want to keep this in (until it is included in regionmask). Not exposed as top level module (only in mesmer.core) as the functionality is only used internally.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (4e2b408) 86.48% compared to head (1e0f792) 86.48%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #275   +/-   ##
=======================================
  Coverage   86.48%   86.48%           
=======================================
  Files          38       38           
  Lines        1547     1547           
=======================================
  Hits         1338     1338           
  Misses        209      209           

Flag	Coverage Δ
unittests	86.48% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
mesmer/core/regionmaskcompat.py	95.45% <ø> (ø)
mesmer/core/mask.py	100.00% <100.00%> (ø)
mesmer/io/load_constant_files.py	95.91% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.