Handle pna_main_parser_input_metadata_t fields in the tc backend's parser

[vbnogueira]

As of now, referencing a field of pna_main_parser_input_metadata_t will cause the it to be generated in eBPF without any translation.

For example:

parser Ingress_Parser(
        packet_in pkt,
        out   my_ingress_headers_t  hdr,
        inout my_ingress_metadata_t meta,
        in    pna_main_parser_input_metadata_t istd)
{
    state mystate {
        ...
        meta->ingress_port = istd.input_port;
        ...
    }
    ...
}

Will generate something like:

mystate: {
    ...
    meta->ingress_port = istd.input_port;
    ...
}

This will cause a compilation error because istd is not defined in the ebpf code. This PR fixes this by either translating the fields to something ebpf understands or simply throwing an error if the field is unsupported.

[vbnogueira]

@komaljai please take a look when you have some time

[vbnogueira]

@komaljai the bazel test is failing, but it seems to be unrelated to the changes in this PR (seems to be something in p4_dpdk)
If that is the case, could we merge this without this test passing?

[fruffy]

This might be a cache problem, let me clear the actions cache.