Add server-side workflow template library

[ohltyler]

Description

This PR removes the placeholder function to fetch hardcoded preset workflows, and replaces it with a dynamically-fetched set of workflows via JSON templates persisted on the server side under server/resources/templates. This allows easy addition and updates to preset workflows; simply adding a valid JSON file will now automatically add to the list of available preset workflows when navigating to the New workflow tab. Dynamic fetching is done via server APIs and preset workflows persisting in redux state. Validation is done when parsing the JSON files (logic is stubbed for now).

Note we may fetch presets and other OOTB configs from the backend or other central repository in the future. That design is still in progress.

To handle this, a variety of cleanup to interfaces and utils fns were made:

• updating WorkflowTemplate and Workflow interfaces to match more closely with the backend
• adding stubbed util fns for handling the conversion of a UI workspace flow -> backend template sub-workflows, and vice-versa
• adding stubbed util fns for validation of UI workspace flows and backend templates
• automatic generation of a UI workspace set of nodes/edges if the saved workflow does not contain it

Demo video below shows the New workflow tab being populated based on the JSONs saved in server-side, as well as some automatically generated placeholder workflows state nodes/edges.

screen-capture.17.webm

Issues Resolved

Resolves #72

Check List

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 20.20%. Comparing base (616b1cb) to head (3237efd).

Additional details and impacted files

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- Coverage   25.42%   20.20%   -5.23%     
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  Files          53       54       +1     
  Lines         763      797      +34     
  Branches       73       74       +1     
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- Hits          194      161      -33     
- Misses        562      630      +68     
+ Partials        7        6       -1     

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