refactor: extract StorageInterface protocol and add InProcessStorageControllerHandle

[vringar]

Summary

• Extract StorageInterface protocol from StorageControllerHandle
• Add InProcessStorageControllerHandle that runs the StorageController asyncio loop in a daemon thread instead of a subprocess, eliminating process spawn overhead for tests

The extension connects to it identically (same TCP protocol). Production code is unchanged.

Stacked on #1125.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 89 lines in your changes missing coverage. Please review.
✅ Project coverage is 36.94%. Comparing base (1be210b) to head (971a1b8).

Files with missing lines	Patch %	Lines
openwpm/storage/in_process_storage.py	0.00%	79 Missing ⚠️
openwpm/storage/storage_interface.py	0.00%	10 Missing ⚠️

❌ Your project check has failed because the head coverage (36.94%) is below the target coverage (40.00%). You can increase the head coverage or adjust the target coverage.

❗ There is a different number of reports uploaded between BASE (1be210b) and HEAD (971a1b8). Click for more details.

HEAD has 4 uploads less than BASE

Flag	BASE (1be210b)	HEAD (971a1b8)
	5	1

Additional details and impacted files

@@                         Coverage Diff                          @@
##           refactor/extract-command-context    #1126      +/-   ##
====================================================================
- Coverage                             44.03%   36.94%   -7.10%     
====================================================================
  Files                                    37       39       +2     
  Lines                                  3522     3611      +89     
====================================================================
- Hits                                   1551     1334     -217     
- Misses                                 1971     2277     +306     

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