Implement a Context Menu for node operations and Cleanup Sidebar Tree

[PintoGideon]

Addresses #1151
Addresses #1147

This PR just nukes the sidebar panel. It will be moved to the Feed Tree in a future PR.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 3.84615% with 100 lines in your changes are missing coverage. Please review.

Project coverage is 30.06%. Comparing base (bac66be) to head (f836015).

Files	Patch %	Lines
src/components/FeedTree/Node.tsx	2.27%	43 Missing ⚠️
src/components/FeedTree/DropdownMenu.tsx	3.12%	31 Missing ⚠️
src/components/AddPipeline/AddPipeline.tsx	0.00%	5 Missing ⚠️
src/components/DeleteNode/index.tsx	0.00%	4 Missing ⚠️
src/components/FeedDetails/index.tsx	0.00%	4 Missing ⚠️
...components/FeedOutputBrowser/FeedOutputBrowser.tsx	20.00%	4 Missing ⚠️
src/components/AddNode/AddNode.tsx	0.00%	3 Missing ⚠️
src/components/NodeDetails/NodeDetails.tsx	0.00%	3 Missing ⚠️
src/components/FeedOutputBrowser/FileBrowser.tsx	0.00%	1 Missing ⚠️
src/components/Feeds/FeedView.tsx	0.00%	1 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1153      +/-   ##
==========================================
+ Coverage   29.09%   30.06%   +0.97%     
==========================================
  Files         200      191       -9     
  Lines        6149     5987     -162     
  Branches     1279     1245      -34     
==========================================
+ Hits         1789     1800      +11     
+ Misses       4246     4078     -168     
+ Partials      114      109       -5     

Flag	Coverage Δ
e2etests	30.06% <3.84%> (+0.97%)	⬆️

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