Description

This PR is a follow-up to #10869.

• Add more tests for %c interpolation
• The error msg of mypy now is bassically the same as CPython. We offer hints for incompatible types.
• Change type of Checkers from Tuple[Callable[[Expression], None], Callable[[Type], None]] to Tuple[Callable[[Expression], None], Callable[[Type], bool]]. check_expr can get a False from check_type and stop generating same error message.

Test Plan

Adds several new test cases.

CPython behaviors:

'%c' % b''   # E: "%c" requires int or char
'%c' % b'ab' # E: "%c" requires int or char
b'%c' % b''   # E: "%c" requires int or char
b'%c' % b'aa' # E: "%c" requires int or char