add option to generate annotations for the tests generated by hypothesis

[ThunderKey]

This adds a annotation argument to all public ghostwriter functions, as well as a --annotations and --no-annotations flag to the CLI. It searches the function for which the tests are generated for type annotations. If the arguments have type annotations, the same will be used for the generated tests.

The generated annotations are not as good as the detected strategies of st.builds, but it sure is a start for people writing tests that requires type hints.

Closes #3546

[Zac-HD]

Note to self: we have a pretty similar helper in strategies/_internal/types.py, which dates back to Python 3.4 or so. We (I) should try porting over to the stdlib version soon and see what breaks.

[Zac-HD]

This is fantastic work, thanks so much @ThunderKey! I'll want to do another read through after the minor comments above are addressed, probably on the weekend, but look forward to shipping this soon!

[ThunderKey]

You're welcome!

Thanks for the tip with defaultdict and the idea of not using the ghostwriter specific _get_params function. I'll fix those shortly.

About moving the detection of the annotations to the _make_test_body: My idea was, that the annotations should be the same for each generated test in the file. For example in the magic function it could be that some of the functions would be generated with annotations and others without. I see the following 3 options. Which do you prefer?

1. Let the ghostwriter mix having annotations and not in the same file.
2. Leave as is, which ensures that it will always add annotations or not add annotations for each file.
3. Pass the detection to _make_test_body, but in the magic function detect it before.

[Zac-HD]

I prefer having/not-having annotations on a per-file basis matches the behavior that you can get by passing the argument to specify which you want. I liked (3) for reduced code duplication, but then we'd need a special case so I'm equally happy with (2).

[Zac-HD]

I updated the docs and then after checking CLI help shortened the argument name; let's merge and release!