Refactor Video Inputs

[ethanwharris]

What does this PR do?

• Refactors video inputs to use the ClassificationInputMixin
• Adds support for from_csv and from_data_frame to VideoClassificationData

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[codecov]

Codecov Report

Merging #1117 (8cb2fcc) into master (d01b5a0) will increase coverage by 0.02%.
The diff coverage is 89.06%.

@@            Coverage Diff             @@
##           master    #1117      +/-   ##
==========================================
+ Coverage   88.50%   88.53%   +0.02%     
==========================================
  Files         286      286              
  Lines       12937    12950      +13     
==========================================
+ Hits        11450    11465      +15     
+ Misses       1487     1485       -2     

Flag	Coverage Δ
unittests	88.53% <89.06%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
flash/video/classification/input.py	75.86% <84.44%> (+0.86%)	⬆️
flash/video/classification/data.py	100.00% <100.00%> (ø)

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[awaelchli]

looks very clean 🤩