Add time tracking feature to boards sidebar

What does this MR do?

• The changes are behind two FFs:
  • :graphql_board_lists
  • :boards_with_swimlanes
• Adds time tracking feature to boards sidebar
  • Adds time_tracker.vue component to board_content_sidebar.vue
• Adds an additional prop "isCollapsibleSidebar" to time_tracker.vue
  • This prop is used to prevent time_tracker.vue from rendering components used when sidebar is collapsed.

Screenshots

Screenshot	Demo
	Screen_Recording_2020-10-22_at_1.18.27_PM

Demo2(w/ limitToHours)
Screen_Recording_2020-10-22_at_1.21.52_PM note that limitToHours is set at an instance level.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

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
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #37102 (closed)