Avoid nested quantifiers with overlapping character space on git url parsing (#1902 (#1913)

* fix (git): match for `\w` instead of `.` for getting user

* change (vcs.git): hold pattern of the regex parts in a dictionary to be consistent over all regexs

* new (vcs.git): test for `parse_url` and some fixes for the regex pattern

* new (vcs.git): test for `parse_url` with string that should fail

* fix (test.vcs.git): make flake8 happy