Move buttons from actionbar to projectchooser

[danirabbit]

Closes #1581

Create a widget instead of using a util.

• Set css name to make sure this is styled as a model button (highlight on hover etc)
• Set the correct accessible role.
• Reverts back to "Open Folder..." as the label for the open button
• more descriptive "Clone Git Repository" since "Clone" is probably not descriptive enough, especially for blind folks
• Add symbolic git icon
• Button closes popover
• Use AccelLabel in case we add accels to this later 🤷‍♀️ and for alignment etc