Bluetooth: Kconfig: Add kconfig options for extended advertising

Add Kconfig options to enable extendend advertising and scanning
support.
Include option to support both types of advertising
commands in case the controller capabilities is not know or the
controller is pluggable.
Include option to only support legacy advertising API, this is to
support the use-case of advertising using different identity than the
scanner or initiator.

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