Add initial support for pipeline properties

[marthacryan]

Added to address elyra-ai/elyra#1699.
Adds a tab to the right side panel and adds the ability to use a textarea and readonly for text inputs:

Uses a given properties config to display the pipeline properties editor. Doesn't currently handle the case that there is none given - in that case, should the tab be removed, or should it just display a message like "No pipeline properties defined"?

Adds pipeline properties into a field pipeline_properties.

Todo:

• Move pipeline properties into app_data in the pipeline JSON

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[codecov-commenter]

Codecov Report

Merging #122 (fa914b0) into master (25b9a0f) will decrease coverage by 1.18%.
The diff coverage is 59.67%.

@@            Coverage Diff             @@
##           master     #122      +/-   ##
==========================================
- Coverage   80.42%   79.23%   -1.19%     
==========================================
  Files          36       40       +4     
  Lines        1272     1315      +43     
  Branches      291      301      +10     
==========================================
+ Hits         1023     1042      +19     
- Misses        195      213      +18     
- Partials       54       60       +6     

Impacted Files	Coverage Δ
...ne-editor/src/CustomFormControls/StringControl.tsx	84.44% <0.00%> (-1.92%)	⬇️
...CustomFormControls/validators/string-validators.ts	73.33% <ø> (ø)
...e-editor/src/properties-panels/properties-utils.ts	100.00% <ø> (ø)
...tor/src/properties-panels/useActiveFormItemShim.ts	100.00% <ø> (ø)
...ditor/src/properties-panels/PipelineProperties.tsx	16.66% <16.66%> (ø)
...kages/pipeline-editor/src/PipelineEditor/index.tsx	44.22% <38.46%> (-0.76%)	⬇️
...e-editor/src/CustomFormControls/DisplayControl.tsx	50.00% <50.00%> (ø)
...e-editor/src/properties-panels/PropertiesPanel.tsx	81.81% <83.33%> (ø)
...ne-editor/src/properties-panels/NodeProperties.tsx	85.71% <85.71%> (ø)
...ckages/pipeline-editor/src/ThemeProvider/styles.ts	93.91% <100.00%> (+0.16%)	⬆️
... and 6 more

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[bourdakos1]

the properties panel refactor looks really good, nice work 😊

just a couple small changes around the form control stuff

[bourdakos1]

LGTM