Add support for compressed files

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 60.00000% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 89.60%. Comparing base (abe5805) to head (990c1fb).

Files	Patch %	Lines
foamlib/_cases.py	40.00%	3 Missing :warning:
foamlib/_files/_io.py	80.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #120 +/- ## ========================================== - Coverage 89.63% 89.60% -0.04% ========================================== Files 9 9 Lines 801 808 +7 ========================================== + Hits 718 724 +6 - Misses 83 84 +1 ```

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