Add support for Android Backups

[Schamper]

Also some miscellaneous cleanup.

Depends on https://github.com/fox-it/dissect.util/pull/33.

Unit tests will follow later.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.29412% with 30 lines in your changes missing coverage. Please review.

Project coverage is 75.17%. Comparing base (1e38f11) to head (69a29b4).

Files	Patch %	Lines
dissect/target/loaders/ab.py	84.65%	29 Missing :warning:
...issect/target/plugins/os/unix/linux/android/_os.py	92.85%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #419      +/-   ##
==========================================
+ Coverage   75.10%   75.17%   +0.06%     
==========================================
  Files         294      295       +1     
  Lines       25130    25315     +185     
==========================================
+ Hits        18875    19031     +156     
- Misses       6255     6284      +29     

Flag	Coverage Δ
unittests	75.17% <85.29%> (+0.06%)	:arrow_up:

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[Miauwkeru]

I was able to verify it now, I did notice there is an issue in firefox.downloads(). Where the moz_anno_attributes does not exist in the table. So rows() is called on a None object.

Additionally, could you add a test for the android stuff in the firefox plugin?