Refactor getStaticPageProps workflowID to project's single active workflow, if no query param

[mcbouslog]

Package:

• app-project

Closes #2910.

Describe your changes:

• refactor Project store view defaultWorkflow (which was not necessarily the default workflow as defined in project.configuration.default_workflow) to singleActiveWorkflow (which is what the returned value is based on)
• refactor ProjectHeaderContainer and all related tests per ^
• remove default from fetchWorkflowsHelper
• refactor getStaticPageProps to set workflowID per singleActiveWorkflow, if no query param

Note - removing references to default workflow in accordance with ADR 34

Helpful explanations that will make your reviewer happy:

• What Zooniverse project should my reviewer use to review UX?
  • (single active workflow) https://local.zooniverse.org:3000/projects/nora-dot-test/planet-finders-beta/classify => not prompted to select workflow
  • https://local.zooniverse.org:3000/projects/msalmon/hms-nhs-the-nautical-health-service/classify?env=production => yes prompted to select workflow
  • (complete workflow) https://local.zooniverse.org:3000/projects/msalmon/hms-nhs-the-nautical-health-service/classify/workflow/18618?env=production => not prompted to select workflow
  • (no active workflows) https://local.zooniverse.org:3000/projects/markb-panoptes/uwworgtest-cleveland-metroparks/classify => prompted but "nothing to classify"
• What user actions should my reviewer step through to review this PR?
  • see list of links and expectations above
• Which storybook stories should be reviewed? - n/a
• Are there plans for follow up PR’s to further fix this bug or develop this feature? - no

Review Checklist

General

• Are the tests passing locally and on Travis?
• Is the documentation up to date?

Components

• Has a storybook story been created or updated?
• Is the component accessible?
  • Can it be used with a screen reader? BBC guide to testing with VoiceOver
  • Can it be used from the keyboard? WebAIM guide to keyboard testing
  • Is it passing accessibility checks in the storybook?

Apps

• Does it work in all major browsers: Firefox, Chrome, Edge, Safari?
• Does it work on mobile?
• Can you yarn panic && yarn bootstrap or docker-compose up --build and app works as expected?

Publishing

• Is the changelog updated?
• Are the dependencies updated for apps and libraries that are using the newly published library?

Post-merging

• Did the app deploy to https://frontend.preview.zooniverse.org/projects/:project-name/:owner or https://frontend.preview.zooniverse.org/about?
• Is the new feature working or bug now fixed?
  • Is there a Talk or blog post written to announce the new feature(s)?
• Is the design working across browsers (Firefox, Chrome, Edge, Safari) and mobile?
  • Is this approved by our designer?
• Is this ready for production deployment?

[eatyourgreens]

Code read looks good. I'll run through the code locally later today but the changes seem harmless. I've suggested clarifying the comments and also using mock data that reflects real API data.

ADR 34 says the following about default workflows, which won't be possible if they're removed completely.

Default workflows programmatically no longer has any meaning. We could still use this to visually indicate a preferred or suggested workflow from the project team in the UI. This is a design question to explore if we are asked for it.

Maybe restrict this PR just to fixing the bug and open a second PR to suggest removing default workflows completely? I've got no strong opinions.

[eatyourgreens]

Changes look good.
https://local.zooniverse.org:3000/projects/nora-dot-eisner/planet-hunters-tess/classify redirects to https://local.zooniverse.org:3000/projects/nora-dot-eisner/planet-hunters-tess/classify/workflow/11235.

https://local.zooniverse.org:3000/projects/pmlogan/poets-and-lovers/classify/workflow/19770 loads a finished workflow by ID.

I've suggested some changes but nothing blocking.