Match pip's behaviour when package name ends with archive extension

[dukecat0]

• [x] I have added an entry to docs/changelog.md

Summary of changes

Match pip's behaviour when package name ends with an archive extension such as .whl, .tar.gz (Treat it as a local path).

Closes #641

Test plan

Tested by running

pipx install black-22.6.0-py3-none-any.whl --verbose

[dukecat0]

It will still change to black-22.6.0-py3-none-any-whl if the file doesn't exist since it may be a valid project name.

Or we should directly raise file not found error? Since a project name like this is really rare.