Accept only-one-sample per project as input to QuaC

QuaC fails when only one sample in input ped file (#34 (closed)). This MR fixes this issue by removing filepath globbing. This MR further adds a system-level testing to capture such errors in future (#35 (closed)).

workflow/rules/coverage_analysis.smk

@@ -124,13 +124,11 @@ rule mosdepth_plot:
         protected(OUT_DIR / "project_level_qc" / "mosdepth" / "mosdepth.html"),
     message:
         "Running mosdepth plotting"
-    params:
-        infiles=lambda wildcards: str(OUT_DIR / f"{{{','.join(SAMPLES)}}}" / "qc" / "mosdepth" / "*.mosdepth.global.dist.txt"),
     shell:
         r"""
         python {input.script} \
             --output {output} \
-            {params.infiles}
+            {input.dist}
         """