Remove deprecations and add docstring to BaseImagingExtractorInterface

[h-mayorquin]

Removing some code whose time has come and adding a docstring to the base imaging class.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.63%. Comparing base (419ab11) to head (3bdaf2a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1126      +/-   ##
==========================================
+ Coverage   90.59%   90.63%   +0.04%     
==========================================
  Files         129      129              
  Lines        8187     8171      -16     
==========================================
- Hits         7417     7406      -11     
+ Misses        770      765       -5     

Flag	Coverage Δ
unittests	90.63% <100.00%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...nterfaces/behavior/fictrac/fictracdatainterface.py	92.30% <ø> (+0.52%)	⬆️
...atainterfaces/ecephys/baselfpextractorinterface.py	100.00% <ø> (ø)
...erfaces/ecephys/baserecordingextractorinterface.py	93.81% <ø> (ø)
...ainterfaces/ophys/baseimagingextractorinterface.py	98.18% <ø> (+3.02%)	⬆️
src/neuroconv/tools/neo/neo.py	77.04% <ø> (+0.85%)	⬆️
...c/neuroconv/tools/spikeinterface/spikeinterface.py	91.05% <ø> (-0.04%)	⬇️
src/neuroconv/tools/testing/mock_interfaces.py	100.00% <100.00%> (ø)