Add support for HTTP Header Authentication

[tweemeterjop]

Some PassiveDNS providers use a custom HTTP Header for user authentication.

This pull request adds support for specifying a custom HTTP header.

It also fixes the mapping to rrtype when the pdns provder outputs the rrtype in lowercase.

[Rafiot]

Thank you very much for the PR.

Very much a detail, but I'd find it nicer to pass a dict instead of a tuple for auth_header, is there any reason you picked a tuple?

Good catch for the rrtype.

[tweemeterjop]

I assumed the auth_header is always a single header with a tuple for header name + value so a tuple is more strict than using a dict. Whats the use case of using a dict for the auth_header? You could also add the possibility to add additional custom headers in the form of a dict but then likely in another param.

[Rafiot]

Fair, it's just you're making the tuple into a dict in the update call. Let's merge it as-is, it is really not a hill I want to die on.