Add an option to enable decoding null bytes from url encoded forms

[Tragetaschen]

Is there an existing issue for this?

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Is your feature request related to a problem? Please describe the problem.

While reading a form, there are two code paths. One is active for UTF8 and ASCII, another is active for all other encodings. The former uses the UrlDecoder and that throws when it decodes a null byte (%00) from a form. The second path on the other hand treats the form as data url and accepts the null byte creating a string instance with a U+0000 code point.

Describe the solution you'd like

I understand that the RFC suggests not allowing null, but having the option in the first path to accept it anyways would certainly help.

Additional context

As a workaround, it's possible to always force the second code path by registering an EncodingProvider and manipulating the request header to include a known charset value that maps to an instance of UTF8Encoding that isn't the Encoding.UTF8 instance.