[FEATURE] ASL quality assurance module

[acsenrafilho]

Is your feature request related to a problem? Please describe.
A module that implements ASL data quality assurance metrics

Describe the solution you'd like
To give quantitative QA metrics for input ASL data

Describe alternatives you've considered
It can be inspired by the DWI/DTI QA metrics already presented in other tools (FSL, Tortoise, etc).

Additional context

• SNR level
• ASL voxel signal proportion (quantify voxel signal difference among tissues in the image)