Bluetooth: host: Add new argument and return code to bt_create_conn_le

Deprecate bt_create_conn_le and rename it to in order to add return
code, new arguments and to follow the established naming convention.

Add API for the application to control the scan parameters of the
initiator role. This allows the application more scheduling control
of the initiator in multi-role scenarios. Also provides options to
configure the initiator for LE Coded PHY for long range support.
We deprecate the old way of creating connection to make the name more
consistent with the rest of the API.

Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>