Rewrite protect_pip_from_modification_on_windows

[uranusjr]

Follow up on #7358 to implement a better logic with less edge cases. The implementation is put in its own module and functions so it can be improved on in the future.

The logic I have in mind is:

• Check whether the command (sys.argv[0]) looks like a path. If it does not (and therefore will be resolved by the shell as a command), use shutil.which to resolve it.
• Check if the path is a file (to exclude the python src\pip case).
• Check if the file is named like a pip wrapper script.
• Emit the error.

[uranusjr]

This PR does not contain any of these yet, but

• I want to put the logic up for feedback.
• Make sure it’s OK to move looks_like_path like this.

[chrahunt]

IMO, taking a "move the file out of the way if deletion fails" approach would be better, then we can remove all of these pip-specific checks and workarounds. Similar to what is suggested in #7533, except not necessarily scheduling deletion on next reboot.

[uranusjr]

Yeah that makes sense. I’m abandoning this for now so this can be discussed more in detail first.