Review pip vendoring

[pombredanne]

In #58 there are several fixes made to pip... yet pip was meant to be vendored as-is and unmodified.
We also lost history in some move... we should clean this up and vendor pip automatically (with vendy that we use already for typecode)

[jayvdb]

The pip vendoring is broken in 0.2.0

[   39s] + pytest-3.8 --ignore=_build.python38 --ignore=_build.python39 --ignore=_build.python310 -v
[   39s] ============================= test session starts ==============================
[   39s] platform linux -- Python 3.8.13, pytest-7.1.2, pluggy-1.0.0 -- /usr/bin/python3.8
[   39s] cachedir: .pytest_cache
[   39s] rootdir: /home/abuild/rpmbuild/BUILD/fetchcode-0.2.0, configfile: pyproject.toml
[   45s] collecting ... collected 12 items / 8 errors
[   45s] 
[   45s] ==================================== ERRORS ====================================
[   45s] ________________ ERROR collecting src/fetchcode/vcs/__init__.py ________________
[   45s] src/fetchcode/vcs/__init__.py:22: in <module>
[   45s]     from fetchcode.vcs.pip._internal.vcs.bazaar import Bazaar
[   45s] /usr/lib/python3.8/site-packages/_pytest/assertion/rewrite.py:168: in exec_module
[   45s]     exec(co, module.__dict__)
[   45s] src/fetchcode/vcs/pip/_internal/vcs/__init__.py:6: in <module>
[   45s]     import fetchcode.vcs.pip._internal.vcs.bazaar
[   45s] /usr/lib/python3.8/site-packages/_pytest/assertion/rewrite.py:168: in exec_module
[   45s]     exec(co, module.__dict__)
[   45s] src/fetchcode/vcs/pip/_internal/vcs/bazaar.py:11: in <module>
[   45s]     from fetchcode.vcs.pip._internal.utils.misc import display_path, rmtree
[   45s] /usr/lib/python3.8/site-packages/_pytest/assertion/rewrite.py:168: in exec_module
[   45s]     exec(co, module.__dict__)
[   45s] src/fetchcode/vcs/pip/_internal/utils/misc.py:29: in <module>
[   45s]     from pip import __version__
[   45s] E   ModuleNotFoundError: No module named 'pip'