Added some FUSE functionalities for macOS

[tiberiu04]

Title

Add macOS FUSE support using fuser crate #4

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Description

This PR adds initial support for macOS by replacing the previous dummy implementation with a real FUSE mount logic using the fuser crate. This allows the rencfs encrypted file system to be mounted and used on macOS, similar to how it works on Linux.

• Introduced conditional compilation in dummy.rs for macOS.
• Implemented MountPointImpl and MountHandleInnerImpl using fuser on macOS.
• Ensured compatibility with the existing Linux structure without affecting other platforms.

Fixes #4

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Type of change

• Feature enhancement (adds macOS support, non-breaking change)

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Checklist:

• I have performed a self-review of my code
• I have tested my code on different platforms (if applicable)
• I have commented my code, particularly in hard-to-understand areas
• I have added necessary documentation (if appropriate)
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

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Additional Context

• This is the first step towards full macOS support.
• The DummyFS is used temporarily; next step would be integrating EncryptedFs as a real Filesystem implementation for macOS.
• Requires testing on a real macOS environment with macFUSE installed.

[Copilot]

Pull Request Overview

This PR introduces initial macOS support for rencfs FUSE mounting by leveraging the fuser crate instead of a dummy implementation.

• Implements macOS-specific mount logic (macos_impl module) using the fuser crate.
• Provides conditional compilation to separate macOS from non-macOS implementations.
• Updates Cargo.toml to include the fuser dependency for macOS.

Reviewed Changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated no comments.

File	Description
src/mount/dummy.rs	Added macOS-specific mount implementation using the fuser crate.
Cargo.toml	Added dependency on the fuser crate for macOS target OS.

Files not reviewed (2)

• data/contents/1/hash/$.: Language not supported
• data/contents/1/ls/$.: Language not supported

Comments suppressed due to low confidence (2)

src/mount/dummy.rs:104

• [nitpick] Consider renaming 'DummyFS' to a name that better conveys its temporary or placeholder nature for future production usage, to reduce any potential confusion during debugging.

struct DummyFS;

src/mount/dummy.rs:49

• New macOS FUSE mounting functionality introduced here lacks automated tests. Please consider adding tests to cover both mounting and unmounting scenarios.

async fn mount(self) -> FsResult<crate::mount::MountHandle> {

[tiberiu04]

When building fuser was causing errors because I added the tokio feature. I removed it and now the build works just fine.