Introduction of StorageManager class

[marcoSanti]

This pull request refactors the CAPIO server logic responsible for handling the storage of files by introducing a dedicated StorageManager class. This centralizes all file storage management into a single, modular unit.

Key Changes:

• Introduced StorageManager: All CAPIO server logic related to files and directories storage has been moved into the new StorageManager class.
• Simplified storage logic: The internal storage structure has been streamlined for clarity and efficiency.
• New Access Methods: Added get and tryGet methods for accessing stored items, including an overload that uses a thread ID (tid) and file descriptor (fd) pair. Class methods have also been renamed to better reflect the naming scheme used in CAPIO classes.
• Error Handling Conformity: Updated error handling to use ERR_EXIT instead of exceptions (throws), ensuring consistency with CAPIO's standard error reporting conventions.
• Includes general cleanup and documentation updates.

[codecov]

Codecov Report

❌ Patch coverage is 69.81132% with 80 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.06%. Comparing base (84bfd83) to head (a27cfda).

Files with missing lines	Patch %	Lines
capio/server/src/storage_manager.cpp	84.70%	16 Missing and 10 partials ⚠️
capio/server/include/remote/handlers/read.hpp	0.00%	16 Missing ⚠️
capio/server/include/handlers/read.hpp	33.33%	10 Missing ⚠️
capio/server/include/handlers/getdents.hpp	25.00%	9 Missing ⚠️
capio/server/include/handlers/seek.hpp	16.66%	5 Missing ⚠️
capio/server/include/remote/handlers/stat.hpp	0.00%	4 Missing ⚠️
capio/server/include/remote/requests.hpp	0.00%	4 Missing ⚠️
capio/server/include/handlers/stat.hpp	40.00%	2 Missing and 1 partial ⚠️
capio/server/include/handlers/rename.hpp	50.00%	0 Missing and 1 partial ⚠️
capio/server/include/handlers/write.hpp	80.00%	1 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #197      +/-   ##
==========================================
- Coverage   56.34%   56.06%   -0.29%     
==========================================
  Files          71       70       -1     
  Lines        3429     3439      +10     
  Branches     2126     2132       +6     
==========================================
- Hits         1932     1928       -4     
- Misses        578     1232     +654     
+ Partials      919      279     -640     

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[GlassOfWhiskey]

Why there is a generic add function and a specialized addDirectory function?

[marcoSanti]

When adding directories, extra steps need to be done compared to simply adding a file. The generic add is used to add a new entry in the storage manager, and when calling the addDirectory, extra steps are performed, which are not usually performed when adding a file.

Moreover, changing to have a single add method, would require to refactor not only method calls naming within the capio_server, but also the logic of the various handlers around capio.