alsabat: add bash test script

alsabat: add bash test script

Add bash script for alsabat feature test. It covers basic alsabat
features, including waveform and wav file generate, playback,
capture and analysis with configurable parameters under different
work modes. (loopback, single line, standalone and local mode)
Usage examples:
        alsabat-test.sh
        alsabat-test.sh plughw:1,0
        alsabat-test.sh plughw:1,0 plughw:1,0

Signed-off-by: Lu, Han <han.lu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>