RootCanal: Implement additional LL tests

Implement LL tests LL/DDI/ADV/BV-01-C and LL/DDI/SCN/BV-18-C.
Fix issues with the python3 binding and async manager to make
the advertising test work.

Bug: 253523072
Test: atest --host rootcanal_ll_test
Change-Id: Ie6ffe0a3de638b551f88f9f11f33bd1da0c6b9ff