Check if Visual QC works correctly for a group of subjects with BBB-ASL data

### Description

 To fix and fine-tune the Visual QC. 
**HENK**: I will also add an image showing a single slice for all PLDs, so we can check if the PLDs are all necessary and if we have a nice division of SNR from early to late phases.

### How to test

xASL_wrp_VisualQC_ASL

### Release notes
Nothing. Duplicate with #1317 
