Add eBPF Testing

[dave-tucker]

What would you like to be added?

There is currently a single BCC unit test which appears to be skipped on CI.
We should have a test that:

1. Load the eBPF probes
2. Makes some assertions about the probes (i.e map sizes are correct, global variables are set etc...)

This test will need to be run using sudo.
It should run in CI.
It should NOT leave the host in a dirty state (i.e leaving eBPF probes attached).

Furthermore, it would be nice to unit test the eBPF code. I'll spend some time looking at that also.

Why is this needed?

There have been a number of regressions since I've re-formatted and simplified some of the eBPF code that could have been caught in code review and/or automated testing. We should ensure that these (or similar) regressions don't occur again.

[dave-tucker]

Also related - testing on different kernels. See #1402 as something we might want to test for.