Dave Tucker f976229477 Support BTF Maps
This commit allows for BTF maps in the .maps ELF section to be parsed.
It reads the necessary information from the BTF section of the ELF file.
While the btf_ids of Keys and Values types are stored, they are not (yet)
used.

When creating a BTF map, we pass the btf_key_type_id and
btf_value_type_id.

Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
..
bpf Support BTF Maps
map_test.rs test: Replace RTF with Rust
name_test.rs test: Replace RTF with Rust
pass.rs test: Replace RTF with Rust
test.rs test: Replace RTF with Rust