Improve epic tree usability and consistency to other widgets

Challenge

• The epic tree styling differs from other similar widgets within work items like issues and MRs.
• The usability of switching views within the epic tree should be improved to allow for better labeling and consistency.
• The epic tree should be easily differentiated from similar objects like Linked epics

Design considerations & flow

• Epic tree vs related epics differentiation
• Epic tree view vs roadmap view
• Ancestor view updates Work on in follow up

Solution

Designs are included in this issue, and ready to be implemented

🎨 UI updates

View Figma doc

• Move the epic & issues and roadmap tabs/seg buttons within the body of the widget
• Move the Show labels option to the body of the widget as well, aligned right in the same row as the view options
• Add a title to the widget. Currently thinking here is Child epics and issues
• Contain the roadmap view within the widget itself