Fix epics select in sidebar for project epics swimlane [RUN AS-IF-FOSS]

What does this MR do?

• Resolves #299159 (closed)

• Adds a link to selected epic in the new sidebar

• Adds a feature spec (#280540 (closed))

  note: there is an on-going effort to turn on :graphql_board_lists for project boards that involves updating a significant portion of the boards feature spec.

To test this feature, visit any project board (not group board) and use group by epics (Please checkout the demo)

Demo

Screen_Recording_2021-03-08_at_10.00.20_AM

Conformity

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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
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