Fix a collection of UI bugs in Perfusion and ModelFit.
Summary:
T30343, T30339 -Add mask info box to GenericDataFitting, MRPerfusion an PETDynamic views.
T30278 - Disable conversion tab for descriptive Brix.
Fix T30341 - Same location for buttons for T1 and T2 conversion
Test Plan: manually
Reviewers: floca, O3 MITK Reviewer Group II
Reviewed By: floca, O3 MITK Reviewer Group II
Maniphest Tasks: T30341
Differential Revision: https://phabricator.mitk.org/D923