MINOR: proxy: Rename accept-invalid-http-* options

MINOR: proxy: Rename accept-invalid-http-* options

With these options, it is possible to accept some invalid messages that may
considered as unsafe and may result as vulnerabilities. The naming is not
explicit enough on this point. These option must really be considered as
dangerous and only used as a temporary workaround. Unfortunately, when used,
it is probably because there are some legacy and unsupported applications in
place. Nevermind. The documentation warns about the use of these
options. Now the name of the options itself is a warning.

So now, "accept-invalid-http-request" and "accept-invalid-http-response"
options are deprecated and replaced by
"accept-unsafe-violations-in-http-request" and
"accept-unsafe-violations-in-http-response" options.