Introduce git sparse checkout

[yakanechi]

What happened:
A few years ago a sparse checkout feature was added to git

This feature allows for minimal cloning, which can speed up the cloning process.
This will also speed up the clone process.

Also, by combining this with the rootDirectory feature, you can clone only under the rootDirectory, so the rootDirectory can provide more purposeful functionality.

What you expected to happen:
Introduce git sparse checkout

How to reproduce it: