Provide universal Arc implementation for non-atomic platforms

[AlixANNERAUD]

This pull request refactors the usage of Arc across the codebase to consistently import it from the new synchronization module, rather than directly from alloc::sync. It also introduces a conditional implementation of Arc that uses either the standard library or a custom version depending on platform atomic support. Additionally, it makes minor dependency and module organization improvements.

Refactoring and Consistency Improvements:

• Replaced direct imports of alloc::sync::Arc with synchronization::Arc in multiple files, ensuring a unified import path for Arc and improving code maintainability (drivers/native/src/devices/window_screen/window.rs, drivers/wasm/src/devices/graphics/mouse.rs, modules/task/src/environment_variable.rs, modules/task/src/join_handle.rs). [1] [2] [3] [4]

Platform Abstraction and Conditional Compilation:

• Introduced a conditional export in modules/synchronization/src/arc/mod.rs to use the standard library's Arc and Weak when atomic operations are available, and a custom arc_lock implementation otherwise.
• Added a new arc module to modules/synchronization, and re-exported its contents through the crate root for easier access.

Dependency and Build Configuration:

• Updated modules/synchronization/Cargo.toml to add critical-section as a dev-dependency for desktop platforms, and ensured embassy-sync is only included for the appropriate targets.