Request headers whose value matches the request URI host are dropped from curl and HTTPie snippets

[harrisleesh]

The HostHeaderFilter in CliOperationRequest is meant to elide only an implicit Host header, but its allow(String name, List<String> value) implementation never inspects the header name:

@Override
public boolean allow(String name, List<String> value) {
    return !(value.isEmpty() || this.getImplicitHostHeader().equals(value.get(0)));
}

The filter is applied to every header, so any header whose first value happens to equal the host (or host:port) of the request URI is silently removed from the generated curl and http commands. For example, on a request to http://localhost/foo, a header X-Forwarded-Host: localhost disappears from the documented commands. A header with an empty value list is also dropped.

Reproduced on main (3ec9c63, 4.0.2-SNAPSHOT) with a CurlRequestSnippetTests case:

expected: "$ curl 'http://localhost/foo' -i -X GET -H 'X-Forwarded-Host: localhost'"
 but was: "$ curl 'http://localhost/foo' -i -X GET"

Expected: only the Host header is subject to the implicit-host elision; all other headers appear in the snippet regardless of their value. I will submit a PR with a fix and test.

[wilkinsona]

Duplicates #1056.