Add pages to theme_preview (#20185)

Added some simple logic + an example of adding pages to the theme
preview. Will be used for organizing theme preview sections.

Release Notes:

- N/A

crates/workspace/Cargo.toml

@@ -61,6 +61,7 @@ theme.workspace = true
 ui.workspace = true
 util.workspace = true
 uuid.workspace = true
+strum.workspace = true
 
 [dev-dependencies]
 call = { workspace = true, features = ["test-support"] }