deprecate more

[davidism]

Deprecate various things I came across while adding typing to the code. These either seem unused or caused issues with typing, or both.

• urls.Href seems to have been replaced by werkzeug.routing.
• utils.detect_utf_encoding was probably used by Flask, so I'm issuing a deprecation warning just in case someone uses an older Flask with Werkzeug 2.0. This function is part of Python's json.loads now.
• CombinedMultiDict and Headers both had a has_key alias for __contains__. has_key has been deprecated since Python 2.
• Request.disable_data_descriptor class attribute. There's an old comment about deprecating the request.data attribute, but I don't think that should be done. shallow=True can be used to the same effect.
• There's an (internal) helper called cache_property, renamed it cache_control_property to avoid confusion with cached_property, especially when using IDEs to find names.
• url_decode_stream had a return_iterator flag that was unused anywhere in the code.
• HTTPException.wrap seems to only be used to create the BadRequestKeyError class. It's more straightforward to create the class manually, and the type system understands it better too.

One that I did not remove was the parse_option_header multiple parameter. It's not used anywhere, but it's the majority of the function, and I think it could be refactored differently later.

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.