Reject raw files without padding if discard partial is not set (#374)

We have no code in aare to deal with RawFiles that have missing packets
if they are not padded to full size or frames with packet loss dropped.

Added: 
- check that we don't try to read files that are not supported
- python bindings for frame discard policy

at least we get the check in: 
closes #171

---------

Co-authored-by: AliceMazzoleni99 <alice.mazzoleni@psi.ch>

python/aare/__init__.py

@@ -22,7 +22,7 @@ from ._aare import (
     RawSubFile,
 )
 from ._aare import Pedestal_d, Pedestal_f, ClusterFinder_Cluster3x3i, VarClusterFinder
-from ._aare import DetectorType, ReadoutMode 
+from ._aare import DetectorType, FrameDiscardPolicy, ReadoutMode
 from ._aare import hitmap
 from ._aare import ROI
 from ._aare import corner