Create test for ALFA

In order to ensure that ALFA runs for different configurations, we need tests. For this do the following:

• create a test sample table (e.g. for parts of chr21.bam) with the information about the sample
• create a test case
• write a bash script that executes snakemake with the proper settings
• adjust .gitlab-ci.yml with the new bash script that executes the ALFA parts