Docstring, variable name, formatting updates to IDEX L1 (#799)

* Various updates to docstrings, variable names, formatting
* Moved pytest fixture that returns test data to conftest.py

docs/source/conf.py

@@ -116,6 +116,7 @@
     (r"py:.*", r".*numpy.int.*"),
     (r"py:.*", r".*np.ndarray.*"),
     (r"py:.*", r".*numpy._typing._array_like._ScalarType_co.*"),
+    (r"py:.*", r".*idex.l1.TRIGGER_DESCRIPTION.*"),
 ]
 
 # Ignore the inherited members from the <instrument>APID IntEnum class

imap_processing/idex/l0/idex_l0.py

@@ -1,19 +1,21 @@
 """Decommutate IDEX CCSDS packets."""
 
 import logging
+from pathlib import Path
+from typing import Union
 
 from imap_processing import decom, imap_module_directory
 
 logger = logging.getLogger(__name__)
 
 
-def decom_packets(packet_file: str) -> list:
+def decom_packets(packet_file: Union[str, Path]) -> list:
     """
     Decom IDEX data packets using IDEX packet definition.
 
     Parameters
     ----------
-    packet_file : str
+    packet_file : pathlib.Path | str
         String to data packet path with filename.
 
     Returns