feat(callstatelib): add a callstate publishable lib

libs/shared/ngrx-callstate-store/src/lib/non-flicker-loader.ts

@@ -0,0 +1,20 @@
+import { combineLatest, map, mapTo, Observable, startWith, timer } from 'rxjs';
+
+/**
+ * Delay the first emition of data$ value. Instead, it emits "true" until duration is elapsed
+ */
+export const nonFlickerLoader = (
+  data$: Observable<boolean>,
+  duration = 300
+): Observable<boolean> => {
+  const isTrueWhileDuration$ = timer(duration).pipe(
+    mapTo(false),
+    startWith(true)
+  );
+
+  return combineLatest([data$, isTrueWhileDuration$]).pipe(
+    map(([data, isTrueWhileDuration]) =>
+      isTrueWhileDuration ? isTrueWhileDuration : data
+    )
+  );
+};