Make the TC BPF programs configurable

[leodido]

I'd like to have a way for TC BPF classifiers to be configured at runtime.

This can be very useful for parametrized programs. For example, the block_ip would benefit from having a hassle-free way to specify the IP to block without recompiling it.

The way to inject data into them is by using eBPF global data.

Yet, the API generation step (which happens at build time) must provide an "interface" to let the users populate them.