🎨 style(MainPage): rename download and upload buttons to use the word Collection instead of Database

The download and upload buttons were renamed to use the word Collection instead of Database to improve the semantics of the application.

src/frontend/src/pages/MainPage/index.tsx

@@ -26,7 +26,7 @@ export default function HomePage() {
             }}
           >
             <Download className="w-4 mr-2" />
-            Download Database
+            Download Collection
           </Button>
           <Button
             variant="primary"
@@ -35,7 +35,7 @@ export default function HomePage() {
             }}
           >
             <Upload className="w-4 mr-2" />
-            Upload Database
+            Upload Collection
           </Button>
           <Button
             variant="primary"