Git via `libgit2/examples/lg2.c` client

## Summary
* `libgit2`'s `examples` directory contains a simple `git` client that seems to have more working functionality than the `dulwich` client (see https://github.com/dulwich/dulwich/issues/876 and https://github.com/dulwich/dulwich/issues/877).
* `main(int argc, char** argv)` is in [lg2.c](https://github.com/libgit2/libgit2/blob/main/examples/lg2.c).
* The examples [seem to be in the public domain](https://github.com/libgit2/libgit2/tree/main/examples#readme), so, hopefully, there won't be any licensing issues.