add Program.Run to allow passing all parameters to BPF_PROG_RUN

[lmb]

Some recent kernel version introduced BPF_PROG_RUN. It's just an alias for BPF_PROG_TEST_RUN but it shows that upstream considers RUN to be a basic primitive on programs. Another thing that has become apparent is that the input required by different types of programs differs wildly.

• For some prog types ctx must be null, for others it's optional
• For some prog types data must be null and ctx is required (SK_LOOKUP)

Instead of TestWithContext I would add a method Program.Run(RunOptions) (RunResult, error). Names TBD. RunOptions contains all the possible fields like Data, Context, etc. RunResult contains data output, context output, etc. Test and Benchmark keep the same API but are wrappers around Run.

cc @ti-mo

Originally posted by @lmb in https://github.com/cilium/ebpf/pull/511#pullrequestreview-823817507

[lmb]

See #537 for some discussion on what the default argument for input should be.

[lmb]

RunOptions should also include Reset, so that program interruption can be handled by the caller.

[dxuuu]

Run(RunOptions) sounds reasonable to me. Adding a reset callback also sounds good. Just lmk on #647 and I'll send an update

[lmb]

This is now in master!