In redirect, change locale_prefix default to False

[jwhitlock]

In redirect, the default value for locale_prefix is True. This expects that a URL will have an optional locale prefix, such as /en-US/the/page, and that the locale should be automatically pre-pended to the resulting redirect pattern. This is probably the right default for many Mozilla projects, including Bedrock and Kuma, but not in a general redirect library.

One solution would be to make locale_prefix default to False in redirect, and add a wrapper functionlocale_redirect that has the old default. This could grow an optional validation routine, for example you could pass a list of expected locales, and if the prefix doesn't match, it could not be treated as a locale. This would avoid treating paths like /foo/bar as locale=foo/.