bts: Introduce new module for performance tests

A new module is created since its tests are aimed at running against
real HW set ups to check performance of the system under high loads.
As a result, tests in here will usually require a specific config file.

One first test is introduced to activate all TCH/H channels and see if
the BTS (+BTS-TRX) can keep on going fine for a while.

Related: OS#4365
Change-Id: I2d5f0043bdee1f8f5edcf46acce79ce547d1333d
2 files changed