"http_server" input: query parameter overwrites header field with the same name

[gramian]

When using the http_server input, the query parameters and header fields are both kept in the metadata. This has the consequence that if a query parameter has the name as a header field, the header field value gets overwritten with the query parameter. This likely hasn't been reported due to the odd chances of query parameters and header field names coinciding (also due to differing capitalization traditions).

As @mihaitodor suggested on Discord, where I asked about this behavior, that extra parameters could be introduced to configure different namespaces (i.e. sub-objects of meta) for query parameters and header fields.

I like this idea as it would also enable to test for request errors 414 (Request URI too long) and 431 (header fields too large) correctly, which is currently not possible.