Add support for an HTTP "network filesystem" using the UEFI's HTTP
stack.
This also supports HTTPS, but TianoCore EDK2 implementations currently crash while fetching loader files.
Only IPv4 is supported at the moment. IPv6 support is planned for a follow-up changeset.
Note that we include some headers from the TianoCore EDK II project in stand/efi/include/Protocol verbatim, including links to the license instead of including the full text.