bpf_test_run_opts should support passing required IRQL

The bpf_test_run_opts structure is defined in libbpf, but it would be useful to be able to pass Windows specific settings when invoking a BPF program for a test run.

Investigate how to do this in a compatible manner and implement it.

Start by inspecting the libbpf definition of bpf_test_run_opts and the code paths that invoke a BPF program for a test run. Determine how a Windows-specific required IRQL can be represented compatibly with existing callers. Done means the setting can be passed during test runs without breaking the existing interface.

Written by the indexing model from the issue text.