tests: bsim_bt: Add BLE connection test with split controller arch

To also cover the new split controller architecture (with a common ULL
and vendor dependent LLL).
Add a connection testcase (without encryption so far) for the nrf52_bsim
configured with the split controller architecture.
This is just the exact same as the Basic_con test but building the test
with CONFIG_BT_LL_SW_SPLIT=y.
Privacy and data lenght extensions are also so far disabled as the
new controller does not yet support them.

Signed-off-by: Alberto Escolar Piedras <alpi@oticon.com>