Add adapter arg commandline argument to otiocat and otioconvert.

[ssteinbach]

Turns out it was only added to otioview. Now its present in otiocat and otioconvert. You can use it like this:
otiocat opentimelineio_contrib/adapters/tests/sample_data/simple.aaf -a simplify=False

[codecov-io]

Codecov Report

Merging #381 into master will decrease coverage by 0.04%.
The diff coverage is 72.41%.

@@            Coverage Diff             @@
##           master     #381      +/-   ##
==========================================
- Coverage   87.46%   87.42%   -0.05%     
==========================================
  Files          63       63              
  Lines        5506     5533      +27     
==========================================
+ Hits         4816     4837      +21     
- Misses        690      696       +6

Impacted Files	Coverage Δ
opentimelineio/console/otioconvert.py	67.3% <69.23%> (+0.64%)	⬆️
opentimelineio/console/otiocat.py	83.33% <75%> (+1.51%)	⬆️

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