Keyboard navigation unreachable dashboard sections

Bug description

In the dashboard, there are many sections and individual components currently not accessible by sequential keyboard navigation. This means it's hard and sometimes impossible for users using screen readers to interface with Gitpod beyond creating a workspace.

Affected components

• OrganizationSelector (when closed, while it is open, it's inner options are focusable)
• the feedback button in the menu
• UserMenu
• Regenerate & Delete context menu items on the Access tokens page
• <ContextMenu>
• Workspace list caret for expanding to include inactive workspaces
• <Dropdown>
• A <Modal>'s close button - see https://github.com/gitpod-io/gitpod/pull/15809
• The Copy button inside of an <InputWithCopy>

Components with double-focus

In some places, a user has to double-click Tab to go over a component. This happens most often on buttons which are also links.

Examples include:

• The /projects Invite Members button
• The New access token button on /user/tokens
• View Usage inside of /user/billing

Related issues

• A sister issue to https://github.com/gitpod-io/gitpod/issues/16723

Further reading

• https://developer.mozilla.org/en-US/docs/Web/Accessibility/Keyboard-navigable_JavaScript_widgets
• https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex

Start by reading the affected dashboard entry points in components/dashboard/src/menu/OrganizationSelector.tsx, Menu.tsx, components/ContextMenu.tsx, DropDown.tsx, Workspaces.tsx, Modal.tsx, InputWithCopy.tsx, and PersonalAccessTokens.tsx. Reproduce the dashboard, access-token, projects, and billing flows with sequential Tab navigation. Done means each listed control is reachable without double focus, including the InputWithCopy Copy button and modal close button.