Rchiodo/allow default theme

[rchiodo]

Allows user to always use the light theme in the
Python Interactive Window

For #4640

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR)
• Title summarizes what is changing
• Has a news entry file (remember to thank yourself!)
• Has sufficient logging.
• Has telemetry for enhancements.
• Unit tests & system/integration tests are added/updated
• Test plan is updated as appropriate
• package-lock.json has been regenerated by running npm install (if dependencies have changed)
• The wiki is updated with any design decisions/details.

[codecov]

Codecov Report

Merging #4770 into master will decrease coverage by 16%.
The diff coverage is 25%.

@@           Coverage Diff            @@
##           master   #4770     +/-   ##
========================================
- Coverage      77%     61%    -15%     
========================================
  Files         449     373     -76     
  Lines       21674   15199   -6475     
  Branches     3554    1257   -2297     
========================================
- Hits        16625    9250   -7375     
- Misses       5045    5744    +699     
- Partials        4     205    +201

Flag	Coverage Δ
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#Windows	?
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[IanMatthewHuff]