Skip over broken tool Python on Windows too

[konstin]

Fixes #16252

[zanieb]

I wonder if we should just accept the possibility of TOCTOU in this edge case and on Windows

1. Check if the canonicalized path exists
2. If it's a trampoline, check if the pointer path exists
3. Invoke the interpreter
4. On exit code 103, if (1) or (2) was false, return the proper error variant

We could also change the order to check (1) and (2) after (4)

[konstin]

Parsing the trampoline is just what I've been looking for!

I'm not worried about TOCTOU bugs, if you're (un)installing Python interpreters in parallel to (un)install a tool using that very Python version, you're already on an error path. Our behavior does not escape, you can't into a half state that otherwise couldn't exist, you always end up with a regularly working tool or with a tool with a regularly broken Python interpreter (with the variant that you could fail mid-installation with a build that needs to call Python if the underlying Python disappeared). Overall, the behavior doesn't get worse if you get into one of you observe a TOCTOU race.