Restructure codebase to follow modern Rust practices

[morr0ne]

While this appears to be a large PR, it's primarily focused on reorganizing the codebase structure to follow modern Rust practices and establish a solid foundation for future development.

Key changes:

• Moved libcorn to the top level directory
• Relocated CLI to dedicated cli folder (no extra lib.rs needed)
• Updated tests and CI configuration to work with the new structure
• Added release profile with proper optimizations
• Updated bench configurations to require appropriate features
• Refined feature declarations to use proper dependency syntax
• Cleaned up and formatted files

Note: It'd recommend to pull this PR locally for review as GitHub's diff view may not clearly represent the structural changes.

Depends on #39

[JakeStanger]

I assume an automatic MD formatter was run on this file? Output looks the same so not concerned, just interested

[JakeStanger]

Few very minor comments, mostly about comments. I'm yet to check in-editor but generally lgtm, cheers again.

Are you able to rebase this one too pls?