refactor(devtools): move get-store-signal to internal

Author: rainerhahnekamp

libs/ngrx-toolkit/src/lib/shared/get-store-signal.ts renamed to libs/ngrx-toolkit/src/lib/devtools/internal/get-store-signal.ts

@@ -1,13 +1,7 @@
-import {
-  EmptyFeatureResult,
-  signalStoreFeature,
-  StateSource,
-  withHooks,
-  withMethods,
-} from '@ngrx/signals';
+import { signalStoreFeatures, withMethods } from '@ngrx/signals';
 import { inject } from '@angular/core';
 import { DevtoolsSyncer } from './internal/devtools-syncer.service';
-import { getStoreSignal } from '../shared/get-store-signal';
+import { getStoreSignal } from './internal/get-store-signal';
 
 export type Action = { type: string };