feat: add exclude patterns support

[tetuaoro]

Description

This PR enhances the leptosfmt command to support excluding files or directories.

Usage

In my case, I need to exclude just one directory out of 5 directories, so instead of including specific directories, I simply use the exclude feature :

leptosfmt src/ -x src/first -x src/secundo/mod.rs

Changes

• added --exclude (-x) argument
• updated get_file_paths function.

I hope this feature is useful to everyone.

[bram209]

thanks!