Investigate if forc requires git binary or runtime libraries and how to prevent it

[kayagokalp]

forc-pkg utilities uses git2-rs which uses libgit2-sys. But a recent report showed that forc fails to operate without first executing apt-get git.

This implies that either:

1. forc relies on git binary somehow in some place
2. apt-get git installs some runtime libraries that libgit2-sys needs

If it is the 2nd option we should investigate if we can vendor it into forc, if it is the 1st option we should make sure we use git2 instead of the actual binary calls