fix colors in log on Windows

[davidism]

No longer requires Click, as click.style wasn't doing what I expected and other utilities weren't much use. Replaced with a simple wrapper with just the styles used. On Windows, style information is only added if Colorama is installed. The handler added to the "werkzeug" logger wraps the stream with colorama.AnsiToWin32 to output the styles correctly.

This means that if the user overrides the logging configuration, they'll get ANSI codes in the output again. However, that was already the case, even before the switch from termcolor to Click. If they're overriding logging, they can also make the decision to call colorama.init() before that to ensure sys.stderr is wrapped globally, but I didn't want Werkzeug to force that on import.

Also considered just removing styles. Until the recent switch to Click very few people ever saw them because termcolor wouldn't have been installed. For now I'll leave them in.

• fixes Fails to color Windows console #1832

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code.
• Add an entry in CHANGES.rst summarizing the change and linking to the issue.
• Add .. versionchanged:: entries in any relevant code docs.
• Run pre-commit hooks and fix any issues.
• Run pytest and tox, no tests failed.