Monorepo support [SG-14535]

Support for possibly huge "mono repositories", by:

• offering a "shallow" clone of the repository
• selectively fetching projects from the repository, using Git's "sparse checkout" feature and "partial clone" feature
• limiting Log graph (and dependent views) to such a fetched project

Support should be implemented in a subtle way to not complicate the GUI for the majority of "plain" repository users.

Related topics:

• Partial Clone Support
• Sparse Checkout Support

Please comment on this topic about your monorepo size:

• Number of projects
• Number of commits overall (git rev-list --all --count)
• Number of files in HEAD overall (git ls-tree -r HEAD | grep -c "")