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/tests/test_RawMasterFile.py

@@ -3,7 +3,7 @@
 import json
 
 import pytest
-from aare import RawMasterFile, ReadoutMode, DetectorType
+from aare import RawMasterFile, ReadoutMode, DetectorType, FrameDiscardPolicy
 
 
 @pytest.mark.withdata
@@ -16,7 +16,15 @@ def test_read_rawfile_quad_eiger_and_compare_to_numpy(test_data_path):
     assert(f.detector_type == DetectorType.Jungfrau)
 
 
-def test_raw_master_file_context_manager(tmp_path):
+@pytest.mark.parametrize(
+    "policy, expected_policy",
+    [
+        ("nodiscard", FrameDiscardPolicy.NoDiscard),
+        ("discard", FrameDiscardPolicy.Discard),
+        ("discardpartial", FrameDiscardPolicy.DiscardPartial),
+    ],
+)
+def test_raw_master_file_context_manager(tmp_path, policy, expected_policy):
     file_name = tmp_path / "run_master_0.json"
     file_name.write_text(json.dumps({
         "Version": 7.2,
@@ -29,10 +37,13 @@ def test_raw_master_file_context_manager(tmp_path):
         "Total Frames": 2,
         "Frames in File": 2,
         "Frame Padding": 1,
-        "Frame Discard Policy": "nodiscard",
+        "Frame Discard Policy": policy,
     }))
 
     
     with RawMasterFile(file_name) as context_file:
         assert context_file.reading_mode == ReadoutMode.UNKNOWN
         assert context_file.detector_type == DetectorType.Jungfrau
+        frame_discard_policy = context_file.frame_discard_policy
+        assert isinstance(frame_discard_policy, FrameDiscardPolicy)
+        assert frame_discard_policy == expected_policy