feat: implement Premium features page using shadcn/ui and Tailwind (#15094)

resolves coder/internal#176

This is a proof of concept to showcase the use of Tailwind + shadcn/ui.
The goal here was to implement a lower complexity page to reduce the
initial risk and highlight the specific global changes needed.

Changes:

- Create a separate version of Premium features content for Enterprise
and OSS users
- Use shadcn/ui button component and setup styling and variants to match
the buttons defined in the Coder Kit Figma.
https://www.figma.com/design/WfqIgsTFXN2BscBSSyXWF8/Coder-kit?node-id=3-1756
- Setup theming using CSS variables and custom Tailwind colors by using
the dark class name on the root element.
- CSS variable design token naming and colors defined in Figma.
https://www.figma.com/design/WfqIgsTFXN2BscBSSyXWF8/Coder-kit?node-id=1-2


<img width="1199" alt="Screenshot 2024-11-01 at 12 46 03 PM"
src="https://github.com/user-attachments/assets/a251450f-8447-405a-9cc4-9f6aad9cd19f">
<img width="1197" alt="Screenshot 2024-11-01 at 12 45 36 PM"
src="https://github.com/user-attachments/assets/e78a5a40-cbdf-4d85-9ffe-873505800fcc">

.vscode/settings.json

@@ -47,10 +47,11 @@
 	"playwright.reuseBrowser": true,
 
 	"[javascript][javascriptreact][json][jsonc][typescript][typescriptreact]": {
-		"editor.defaultFormatter": "biomejs.biome"
-		// "editor.codeActionsOnSave": {
-		//   "source.organizeImports.biome": "explicit"
-		// }
+		"editor.defaultFormatter": "biomejs.biome",
+		"editor.codeActionsOnSave": {
+			"quickfix.biome": "explicit"
+			//   "source.organizeImports.biome": "explicit"
+		}
 	},
 
 	"[css][html][markdown][yaml]": {