stubtest_third_party.py will now only print a single line when the test
succeeds for a certain distribution, unless the "-v" option is given.
When the test fails or "-v" is given, will still print the full output.
The success status is now colored to make spotting failures easier.
stdout/stderr is now used consistently: The distribution name and
success status is always printed to stdout, all other output goes to
stderr. Running the script with "2>/dev/null" will only show the success
status of the test, one per line.
```
In [4]: ast.dump(ast.parse('f"{x!r}"'))
Out[4]: "Module(body=[Expr(value=JoinedStr(values=[FormattedValue(value=Name(id='x', ctx=Load()), conversion=114)]))], type_ignores=[])"
In [5]: ast.dump(ast.parse('f"{x}"'))
Out[5]: "Module(body=[Expr(value=JoinedStr(values=[FormattedValue(value=Name(id='x', ctx=Load()), conversion=-1)]))], type_ignores=[])"
```
(On 3.9 but I don't think this has changed since 3.6.)
The stdlib also assumes this: https://github.com/python/cpython/blob/main/Lib/ast.py#L1211 (`chr(None)` doesn't work).
- mypy_test and pyright no longer just test the stubs, they now also test other parts of typeshed as well.
- pytype_test.py can now be run on 3.10, meaning the whole test suite can now also be run on 3.10.
- Various test scripts now have from `__future__ import annotations`, meaning they can now only be run on 3.7+.
- Clean up the description of pyright_test.py, which had a slightly confusing wording.
- Also fix the `--dry-run` config option in mypy_test.py, which I accidentally broke in #7746
- Add several type hints to untyped functions.
- While we're at it, upgrade several annotations to use modern syntax by using `from __future__ import annotations`. This means that the tests can't be run on Python 3.6, but 3.6 is EOL, and it is already the case that some scripts in this directory can only be run on more recent Python versions. E.g. `check_new_syntax.py` uses `ast.unparse`, which is only available in Python 3.9+.
- Fix a few pieces of code that didn't type check.
