feat(cli): Add dir_review CLI Command

[Nauscar]

I found this command useful when indexing an entire workspace in a large Rust codebase, and reviewing relevant crates (directories) one at a time.

[mpekatsoula]

Thanks a lot for your patches @Nauscar . Two nitpicks on this one:

1. I think review_dir should treat relative paths as relative to --codebase-path. For example, if I run:
   metis --codebase-path /tmp/project --command "review_dir src"
   I’d expect it to review /tmp/project/src, but with the current code it walks src relative to the current working directory.

2. review_dir should follow the same quiet/non-interactive behavior as review_code. Right now it always goes through the progress UI path, so --quiet / non-interactive output won’t be as clean as the other review commands

[Nauscar]

Appreciate the feedback @mpekatsoula. I believe I have resolved the two items with the latest commit. Please let me know if you prefer a different approach to the minor code refactoring I have done and I can take another pass.

1. Usage of os.path.join to concatenate dir_path and tested with uv run metis --quiet --codebase-path /workspaces/metis --non-interactive --command "review_dir <subdir>".

2. Created a shared function _review_code and added optional kwargs parameters to other supporting functions to support different code_files as input.