In investigating #7947 it has become clear that the storage component of go-git repositories needs closing.

This PR adds this Close function and adds the Close functions as necessary.

In TransferOwnership the ctx.Repo.GitRepo is closed if it is open to help prevent the risk of multiple open files.

Fixes #7947

* move code.gitea.io/git to code.gitea.io/gitea/modules/git

* fix imports

* fix fmt

* fix misspell

* remove wrong tests data

* fix unit tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* enable Debug to trace the failure tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* comment commit count tests since git clone depth is 50

* fix tests

* update from code.gitea.io/git

* revert change to makefile