Make tooltip accessible

[rachelruderman]

Tooltip should always be accessible by keyboard users and should have option to be hidden for screenreader users.

Extra credit: whenever the tooltip duplicates the existing screenreader content, it should not be in the a11y tree, but it should be available for keyboard readers on focus)

[rockhold]

The corresponding Jira logged for the A11y team that would benefit from an accessible tooltip component is at https://cypress-io.atlassian.net/browse/CP-2597. This ticket is not planned for Q2, but it's also not something we'd likely touch without the tooltip component being ready first.

Heads up, @cbfrance :)