Netebpfext fuzzer should fuzz all 4 bind and bind release operations

### Describe the feature you'd like supported

Right now only `test_bind_ipv4` is tested in `tests/libfuzzer/netebpfext_fuzzer/libfuzz_harness.cpp`. We should have tests for all 4 operations:
- test_bind_ipv4
- test_bind_ipv6
- test_bind_release_ipv4
- test_bind_release_ipv6

### Proposed solution

Add the missing 3 mock/test functions to usersim, and add the tests to the netebpfext fuzzer.

### Additional context

_No response_