feat: Add date-picker to the Edit Task modal

[ilandikov]

Types of changes

Done by pairing with @claremacrae

Changes visible to users:

• New feature (prefix: feat - non-breaking change which adds functionality)
  • Issue/discussion:
    • Add a date-picker/calendar button to the Postpone menu - and/or other more convenient locations #2649
    • Implement date picker UI for editing dates in Add/Edit modal #2190

Description

• add date picker for the dates in the Edit Task modal
• fix helper function testing that an element has been rendered (getAndCheckRenderedElement())

Motivation and Context

• Quicker way to select dates in the Edit Task modal

How has this been tested?

• Unit tests
• Exploratory testing

Screenshots (if appropriate)

Date.Picker.in.EDit.Task.Modal.mp4

Checklist

• My code follows the code style of this project and passes yarn run lint.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• My change has adequate Unit Test coverage.

Terms

• My contribution follows this project's contributing guide
• I agree to follow this project's Code of Conduct

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[claremacrae]

I've added a short video of it in action, on a Mac.

[claremacrae]

Brilliant - thank you @ilandikov!