include .pyw files by default when linting and formatting (#20458)

- Adds test cases exercising file selection by extension with
`--preview` enabled and disabled.
- Adds `INCLUDE_PREVIEW` with file patterns including `*.pyw`.
- In global preview mode, default configuration selects patterns from
`INCLUDE_PREVIEW`.
- Manually tested ruff server with local vscode for both formatting and
linting of a `.pyw` file.

Closes #13246

Author: amyreese