ext2: add compatibility with libstorage

[jmaksymowicz]

Modified libext2 to make it compatible with libstorage. This will make the filesystem driver compatible with storage device drivers based on libstorage.

Description

Message handling performed by the libext2_handler was split into separate functions that are compatible with the libstorage API for file systems.

Compatibility with pc-ata storage driver (that uses the current API for handling ext2 filesystems) was not affected.

Additionally, length checks on file names were added (previously name lengths could cause integer overflow).

Motivation and Context

ext2 filesystem would be useful for data exchange using SD cards as ext2 can be easily mounted on many host PC operating systems.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: ia32-generic-qemu, armv7a9-zynq7000-zturn

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work (list the PRs, preferably in merge-order).
• I will merge this PR by myself when appropriate.

[github-actions]

Unit Test Results

5 949 tests  +215   5 296 ✔️ +201   30m 19s ⏱️ + 3m 1s
   325 suites +  14      653 💤 +  14 
       1 files   ±    0          0 ❌ ±    0 

Results for commit 350261d. ± Comparison against base commit c4fd8de.