dulwich: properly patch credentials

[efiop]

From @dtrifiro

I've had a quick look. Need to fix the clone method in scmrepo.git.backends.dulwich, it doesn't use the GitCredentials client. This needs to also be done in other methods which use get_transport_and_path

iterative/dvc#7670

Looks like we need to copypaste clone(and other) implementations from dulwich and use our client instead of relying on get_transport_and_path.

[sisp]

See iterative/dvc#7670 (comment). This is really a blocker for macOS users. 🙁

[dtrifiro]

My initial observations were not correct, the client is patched correctly and the following code works for private repos which require credential helpers on MacOS:

from scmrepo.git import Git

git = Git(".")
git.clone("https://github.com/dtrifiro/a-private-repo", "a-private-repo")
# or, explicitly using the dulwich backend:
git.dulwich.clone("https://github.com/dtrifiro/a-private-repo", "a-private-repo")