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

[h-mayorquin]

As we are updating roiextractors here this should close #1108

[alessandratrapani]

Thank you Heberto! This looks good to me!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.60%. Comparing base (cbf68d4) to head (61f2c4b).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1125      +/-   ##
==========================================
+ Coverage   90.55%   90.60%   +0.04%     
==========================================
  Files         129      129              
  Lines        8187     8174      -13     
==========================================
- Hits         7414     7406       -8     
+ Misses        773      768       -5     

Flag	Coverage Δ
unittests	90.60% <100.00%> (+0.04%)	⬆️

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Files with missing lines	Coverage Δ
...atainterfaces/behavior/video/videodatainterface.py	93.54% <ø> (-0.09%)	⬇️
...ainterfaces/ophys/baseimagingextractorinterface.py	98.18% <ø> (+3.02%)	⬆️
src/neuroconv/tools/roiextractors/roiextractors.py	82.41% <100.00%> (+0.18%)	⬆️
src/neuroconv/tools/testing/mock_interfaces.py	100.00% <ø> (ø)