Move group settings to modal

[TomRomeo]

Description

As we want to move away from different tabs in subpages, we have to change the position for settings of groups.
Instead of the settings page that we had before, the settings should now be opened in a modal.

Steps

• Add settings icon to the group page
• Refactor CreateGroupModal to GroupModal
• Accept a group entity as optional input
• Conditionally change modal title and button
• Add groupType setting to the modal
• Conditionally add the leave and delete button to the modal
• Remove Settings from TabBar on the groups page