Responses with status codes 1xx, 204 or 304 don't have a response body. For
these, don't parse these headers:
- Content-Encoding
- Content-Length
- Content-Range
- Last-Modified
- Transfer-Encoding
This change ensures that HTTP/2 upgrades work even if a
"Content-Length: 0" or a "Transfer-Encoding: chunked" header is present.
Co-authored-by: Daniel Stenberg
Closes#3702Fixes#3968Closes#3977
