removed duplicate functions

src/app/core/json-patch/selectors.ts

-// @TODO: Merge with keySelector function present in 'src/app/core/shared/selectors.ts'
-import { createSelector, MemoizedSelector, Selector } from '@ngrx/store';
-import { hasValue } from '../../shared/empty.util';
+import { MemoizedSelector } from '@ngrx/store';
 import { coreSelector, CoreState } from '../core.reducers';
 import { JsonPatchOperationsEntry, JsonPatchOperationsResourceEntry } from './json-patch-operations.reducer';
-
-export function keySelector<T, V>(parentSelector: Selector<any, any>, subState: string, key: string): MemoizedSelector<T, V> {
-  return createSelector(parentSelector, (state: T) => {
-    if (hasValue(state[subState])) {
-      return state[subState][key];
-    } else {
-      return undefined;
-    }
-  });
-}
-
-export function subStateSelector<T, V>(parentSelector: Selector<any, any>, subState: string): MemoizedSelector<T, V> {
-  return createSelector(parentSelector, (state: T) => {
-    if (hasValue(state[subState])) {
-      return state[subState];
-    } else {
-      return undefined;
-    }
-  });
-}
+import { keySelector, subStateSelector } from '../../submission/selectors';
 
 /**
  * Return MemoizedSelector to select all jsonPatchOperations for a specified resource type, stored in the state