providers/base: add fscrypt test (New)

[fhost]

New: Add a small fscrypt test into the base provider, in its own category.

Description

The new fscrypt test generates an ext4 disk image, mount it and setup fscrypt.
Then it creates a file in the disk image mountpoint, locks it and verifies that the file is not accessible anymore. Finally, it unlocks it and check that the file is accessible and its content is correct.

Tests

checkbox-cli, select automated fscrypt test, run the test plan. Tested on my laptop and on my project device (qualcomm arm64 device). Testing with fscrypt already setup and not setup.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.69%. Comparing base (a65231d) to head (cef64d9).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2215      +/-   ##
==========================================
+ Coverage   53.63%   53.69%   +0.05%     
==========================================
  Files         401      402       +1     
  Lines       43116    43169      +53     
  Branches     7990     8001      +11     
==========================================
+ Hits        23127    23180      +53     
- Misses      19174    19177       +3     
+ Partials      815      812       -3     

Flag	Coverage Δ
provider-base	31.13% <100.00%> (+0.22%)	⬆️

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