Use new enum string APIs

[grantseltzer]

libbpf 1.0 has 4 new APIs for treating enums as strings:

• [x] libbpf_bpf_prog_type_str()
• [x] libbpf_bpf_map_type_str()
• [x] libbpf_bpf_attach_type_str()
• [ ] libbpf_bpf_link_type_str() requires #373

These can possibly be used in our maps that map types into strings.

[geyslan]

Being tackled by https://github.com/aquasecurity/libbpfgo/pull/372.

The libbpf_bpf_link_type_str wasn't managed since LinkType is not 1:1 with libbpf. It needs to be handled in a different task.