Bluetooth: controller: Kconfig option for advanced scheduling

Add Kconfig option to enable advanced scheduling in the
controller.

Enable non-overlapping placement of observer, initiator and
master roles in timespace. Uses window offset in connection
updates and uses connection parameter request in slave role
to negotiate non-overlapping placement with active master
roles to avoid slave roles drifting into active master
roles in the local controller.

This feature maximizes the average data transmission amongst
active concurrent master and slave connections while other
observer, initiator, master or slave roles are active in the
local controller.

Disabling this feature will lead to overlapping role in
timespace leading to skipped events amongst active roles.

Change-id: I16e4e6c3ca99f93987ab86924af0cb9d76bdbc7e
Signed-off-by: Vinayak Chettimada <vinayak.kariappa.chettimada@nordicsemi.no>