Add Support for Downloading Package Using Commit Hash as the Reference

[threeal]

This issue highlights a problem in the cdeps_download_package function, where the current implementation cannot be used to check out a package version based on a commit hash. Currently, cloning a Git repository with the -b option only works when using a branch or tag.

To support commit hashes, we need an alternative method to download and check out a specific version of a package. One approach is to fetch the specific reference and check out that reference after cloning the package. For example, while the current command to download the package is:

git clone -b <ref> --depth 1 <url> <dir> 

We can modify it to:

git clone --no-checkout --depth 1 <url> <dir>
git fetch origin --depth 1 <ref>
git checkout <ref>

This way, the function will support specifying versions using commit hashes, in addition to branch and tag names.