Extend user settings to allow users to set "hideShareSettings"

This is the backend card for extending the user's settings to enable them to "hideShareButtons"

@markeharding rolled out the share toolbar and the community requests being able to turn this off

• [] extend the user entity to be able to save "hideShareButtons"
• [] v1/settings should update the user with the new settings
• [] unit tests to make sure the updated user model saves / exports