ENH: Profiler follow up

[ZLLentz]

Description

• Make profiler_context use a non-global profiler by default
• Allow the global profiler to be reset
• Be more heavy-handed in ignoring on-import errors and warnings
• Show the unit before printing all the profiles
• Add a min_threshold argument for omitting smaller execution times
• Add a message for when no profiles were above the threshold, rather than just blank output

Motivation and Context

I want to keep this easy to use while not locking the use case into "call this one time only please"

How Has This Been Tested?

Interactively only

Where Has This Been Documented?

docstrings only

[ZLLentz]

Reverting to draft because there are more follow-ups that can be addressed!

[ZLLentz]

I think this resolves everything that can be handled quickly.
The async thing will be resolved once we start running with newer versions of line_profiler.

[ZLLentz]

On my windows box I was able to run with sys.modules as the source module list with only one minor problem: a couple modules print text on import. I didn't feel like clobbering the standard output so I left it as-is.

All of the previously problematic submodules are silently skipped.

[tangkong]

I'm sorry this PR made you do such horrible things :(

[ZLLentz]

Forgive me, for I have sinned

[tangkong]

Looks good to me, I'm excited to use it out in the field.

[klauer]

This looks clean to me. I like the new functionality.

The only recommendation I have is that a save_results that takes a file-like object would be useful from an API standpoint. It would allow for using in-memory StringIO, easier testing, and so on.

And then I believe print_results and save_results_to_file effectively then rely on the same underlying code (as sys.stdout, sys.stderr, and open() as fp are all output streams/file-like objects)

[ZLLentz]

Yeah, I can do that- that's how py-spy's api is under the hood too. print_results and save_results were originally just thin helpers, now they can be merged into an underlying call and made thin again. Next PR.