RootCanal: Implement additional LL advertising tests

- LL/DDI/ADV/BV-15-C
- LL/DDI/ADV/BV-16-C
- LL/DDI/ADV/BV-17-C
- LL/DDI/ADV/BV-18-C
- LL/DDI/ADV/BV-19-C
- LL/DDI/ADV/BV-20-C
- LL/DDI/ADV/BV-21-C

Bug: 253523072
Test: atest rootcanal_ll_test
Change-Id: Id447dd5acf84cc2895ae2825cfa63e6db1f59e62