Add always_write_timestamps conversion option to imaging interfaces

[h-mayorquin]

This was discussed in the context of the Cai project with @alessandratrapani

Similar to this one for the ecephys side:
#1091

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.56%. Comparing base (419ab11) to head (d59c19d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1125      +/-   ##
==========================================
- Coverage   90.59%   90.56%   -0.04%     
==========================================
  Files         129      129              
  Lines        8187     8190       +3     
==========================================
  Hits         7417     7417              
- Misses        770      773       +3     

Flag	Coverage Δ
unittests	90.56% <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
...atainterfaces/behavior/video/videodatainterface.py	93.54% <ø> (-0.09%)	⬇️
...ainterfaces/ophys/baseimagingextractorinterface.py	95.16% <ø> (ø)
src/neuroconv/tools/roiextractors/roiextractors.py	82.41% <100.00%> (+0.18%)	⬆️
src/neuroconv/tools/testing/mock_interfaces.py	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

[h-mayorquin]

As we are updating roiextractors here this should close #1108