Migrate tests in connected_cte_req to new ZTEST API.
Remove main.c source file because is unncessary when automatic
unit tests registration is available.
Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>
Before thic commit the bluetooth/df unit tests subdirectory contained
connectionless CTE TX verification. Due to the implementation of
connectionless CTE RX new set of tests will be provided.
The new functionality requires different: configuration and common
setup code. Because of that, current test code was moved to
connectionless_cte_tx subdirectory.
Code shared by all DF tests is moved to common subdirectory.
Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>
