Set name for SnapController (#3052)

`SnapController`'s name was set to `string` rather than
`"SnapController"`, which causes some problems with type inference in
MetaMask/metamask-extension#30034.

Author: Mrtenz

packages/snaps-controllers/src/snaps/SnapController.ts

@@ -825,7 +825,7 @@ const name = 'SnapController';
  */
 
 export class SnapController extends BaseController<
-  string,
+  typeof name,
   SnapControllerState,
   SnapControllerMessenger
 > {