Resolve #3545855 "Followup for 3541027"

Closes #3545855.

• Updates the design of the modal while also adhering to existing patterns.

• Fixes the button nested within a button issue in the TemplateList component. (see bullet 1️⃣ below)

• Provides messaging when there are no more available templates.

• Adds cache invalidation for ViewModes.

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@mred9 I hope you don't mind, but while reviewing I found a couple of bugs and opportunities to clean up some code that has somewhat inflated the scope of this issue. In addition to your changes above I have

• Implemented/fixed the right click context menu on Templates and Pages. Now you can right click OR click the "..." button
• Fixed the CSS where several SidebarNodes had the "grab" css cursor but were not draggable (Templates, Pages)
• Fixed an issue where the horizontal dots icon disappeared when the context menu was opened.
• Centralised the Folders into a new SidebarFolder component that is now used by both Manage Library and Templates panels.
• Added the name of the thing that was right clicked as a label at the top of the context menu.
• Fixed animation when expanding/collapsing folders
• Fixed animation when expanding/collapsing Error details in the Publish Review panel
• Fixed tests and moved the snapshots to external files to make them easier to update in future.
• 1️⃣ Slightly changed the implementation of how you fixed the "nested button" issue. Instead of a <Flex> with onClick={() => setIsOpen(!isOpen)} I wrapped each clickable element with a separate <Collapsible.Trigger asChild> which adds additional a11y attributes.