refactor: improved core barrel exports and Application class (#10286)

BREAKING CHANGES:

`Application.orientation` is no longer a function.

Migration: Remove `()` from the `Application.orientation()` call:
```diff
import { Application } from "@nativescript/core";

-console.log(Application.orientation());
+console.log(Application.orientation);
```


`Application.systemAppearance` is no longer a function.

Migration: Remove `()` from the `Application.systemAppearance()` call:
```diff
import { Application } from "@nativescript/core";

-console.log(Application.systemAppearance());
+console.log(Application.systemAppearance);
```

.prettierrc.json

@@ -1,6 +1,6 @@
 {
-  "useTabs": true,
-  "printWidth": 600,
-  "tabWidth": 2,
-  "singleQuote": true
-}
+	"useTabs": true,
+	"printWidth": 600,
+	"tabWidth": 2,
+	"singleQuote": true
+}