Improved accessibility for activity toggle.

[pavkout]

Changes activity toggle component to use Links for changing the active activity.
This makes the activity toggle keyboard accessible.

Closes #4927

Changelog(Improvements): The activity toggle is now keyboard accessible

[marckong]

This looks good to me. I added some changes to this PR though (it seems to be the custom in Insomnia we push to the PR branch directly). These are the changes;

• removed the useSelector usages in ActivityToggle component and passed props instead to make this component more independent and easy to test. useSelector does some magic read from the database, which requires domain knowledge and also test setup for the database wire up with redux.
• added unit test cases to check the rendering and behaviors of the component based on user events.

[gatzjames]

Thanks for the contribution!
This looks and works great and it's always nice to see contributions that improve the app's accessibility!

[pavkout]

@gatzjames Don't mention. It's my pleasure!