Update ActionController::UrlFor request contract [ci-skip]
Update ActionController::UrlFor request contract [ci-skip]

Using a `request` object that only "responds to the `host`,
`optional_port`, `protocol`, and `symbolized_path_parameter` methods"
has not been possible for a long time.  For example,
`symbolized_path_parameter` was renamed to `path_parameters` (without
deprecation) in 925bd975663df2e0e8613507a7c95a6945a277ac.  And
`request.routes` and `request.original_script_name` methods became
required in 87a75910640b83a677099198ccb3317d9850c204.  And a
`request.engine_script_name` method became required in
4080dd2f244e7c4d140f8724c2075102ea9db36e.

Therefore, this commit updates the documentation to simply require
an `ActionDispatch::Request` instance.

rails/rails,rails/rails,rails/rails,rails/rails