Collapsible dictionary updates

[toasted-nutbread]

This change adds two new modes for dictionary collapsing and adds some documentation for how to configure the appearance.

• Not collapsible - Definitions will not be collapsed.
• Collapsed - Definitions will show a collapse button if their size exceeds the max height, and they will be collapsed by default.
• Expanded - Definitions will show a collapse button if their size exceeds the max height, and they will be expanded by default.
• Force collapsed (new) - Definitions will always show a collapse button, and they will be collapsed by default.
• Force expanded (new) - Definitions will always show a collapse button, and they will be expanded by default.

Resolves #2168.