feat: git source with host git

[swarnimarun]

TODO:

• Create the POC for host git.
• Get the code working on unix systems at least.
• Add basic unit tests from git_source to host git source.
• Refactor the code, remove redundant code, remove unwraps, improve error messages and reporting.
• Remove feature git, and ensure CI runs work.
• Handle lack of git or git-lfs gracefully.
• Write E2E test.
• Windows path issues (too vague to list, out of 3 tests, last one is broken on windows, perhaps 2/3 is a good thing?)...
• Fix bugs on all platforms.
• Look into why conda-build performs "mirror", and if we should consider mirrors as well.

TODO in a separate PR:

• Figure out and ensure ssh auth works by default on all platforms with all configurations.
• Use mirrored clones over normal clones.
• Write tests for all aspects (clone from git path, non-standard revs(hash, tags, branches, etc), use of cache, etc.)

[swarnimarun]

This has both unit and E2E tests, but I am doing some user testing of my own, to test out all the features, will create a separate PR with more E2E tests or add more cases to the present E2E test.