perf: don't recreate items list twice while filtering (#154)

- when we are filtering, the previous code was calling `initListItems()` and then `updateSelected()` which both recreate the rows list, there's no need to do it twice when we can simply pass it from the 1st pass to the 2nd method for other transformation

lib/src/MultipleSelectInstance.ts

@@ -424,7 +424,7 @@ export class MultipleSelectInstance {
     this.initListItems();
   }
 
-  protected initListItems() {
+  protected initListItems(): HtmlStruct[] {
     let offset = 0;
     const rows = this.getListRows();
 
@@ -483,16 +483,15 @@ export class MultipleSelectInstance {
       this.virtualScroll = null;
     }
     this.events();
+
+    return rows;
   }
 
   protected getListRows(): HtmlStruct[] {
     const rows: HtmlStruct[] = [];
     this.updateData = [];
-    // console.time('perf');
-
     this.data?.forEach((row) => rows.push(...this.initListItem(row)));
     rows.push({ tagName: 'li', props: { className: 'ms-no-results', textContent: this.formatNoMatchesFound() } });
-    // console.timeEnd('perf');
 
     return rows;
   }
@@ -1061,7 +1060,7 @@ export class MultipleSelectInstance {
     }
   }
 
-  protected updateSelected() {
+  protected updateSelected(rows?: HtmlStruct[]) {
     for (let i = this.updateDataStart!; i < this.updateDataEnd!; i++) {
       const row = this.updateData[i];
       const inputElm = this.dropElm.querySelector<HTMLInputElement>(`input[data-key=${row._key}]`);
@@ -1088,7 +1087,7 @@ export class MultipleSelectInstance {
     toggleElement(this.noResultsElm, noResult);
 
     if (this.virtualScroll) {
-      this.virtualScroll.rows = this.getListRows();
+      this.virtualScroll.rows = rows ?? this.getListRows(); // recreate the rows list only when not already created
     }
   }
 
@@ -1366,9 +1365,9 @@ export class MultipleSelectInstance {
       }
     }
 
-    this.initListItems();
+    const rows = this.initListItems();
     this.initSelected(ignoreTrigger);
-    this.updateSelected();
+    this.updateSelected(rows); // no need to recreate the rows list twice
 
     if (!ignoreTrigger) {
       this.options.onFilter(originalSearch);