improve initialization and types

packages/overlayscrollbars/src/setups/scrollbarsSetup/scrollbarsSetup.initialization.ts

@@ -0,0 +1,27 @@
+import type {
+  InitializationTargetElement,
+  InitializtationElementStrategy,
+  DynamicInitializationElement,
+} from 'initialization';
+
+export type ScrollbarsDynamicInitializationElement = DynamicInitializationElement<
+  [target: InitializationTargetElement, host: HTMLElement, viewport: HTMLElement]
+>;
+
+/**
+ * Object for special initialization.
+ *
+ * If element is provided, the provided element takes all its responsibilities.
+ * DOM hierarchy isn't checked in this case, its assumed that hieararchy is correct in such a case.
+ *
+ * Null or Undefined means that the environment initialization strategy is used.
+ */
+export interface ScrollbarsInitialization {
+  scrollbarsSlot?: ScrollbarsDynamicInitializationElement;
+}
+
+export type ScrollbarsInitializationStrategy = {
+  [K in keyof ScrollbarsInitialization as `_${K}`]: InitializtationElementStrategy<
+    ScrollbarsInitialization[K]
+  >;
+};