[RFE] Inspect a gadget in details

[alban]

Current situation

A gadget can be imspected with the ig image inspect command (implemented in #3382). But it does not give all possible details.

See #3382 (review)

Impact

When gadget developers are trying to debug their gadgets, they cannot easily inspect the different layers, decompile, list the ebpf programs and ebpf maps etc.

Ideal future situation

It should be possible to get the following information from a gadget:

• list of architectures supported by the gadget
• list of layers
• information from gadget.yaml:
  • list of ebpf params
  • list of data sources with the list of fields
• information from the ebpf module
  • list of sections (so I can see kprobe/sys_mount)
  • list of ebpf maps with their types (so I don't have to use readelf and objdump)
  • show bpf bytecode + source (when available in ELF sections) of requested ebpf programs
• information from the wasm module
  • what gadgetAPIVersion does it use?
  • which wasm upcalls does it make?

Implementation options

Additionally, it would be nice to have an implementation both in ig and in a wasm module to be reusable on websites. For the second case, this probably means we can't use the cilium/ebpf package.

Additional information

I gave it a try with wasm and came up with the following website:

https://github.com/alban/bpfanalyser
https://alban.github.io/bpfanalyser/

Useful changes in cilium/ebpf: cilium/ebpf#1552