feat: add FileSystemFileHandle support

Author: tomayac

src/file-selector.ts

@@ -121,6 +121,10 @@ function flatten<T>(items: any[]): T[] {
 }
 
 function fromDataTransferItem(item: DataTransferItem) {
+    if ('getAsFileSystemHandle' in DataTransferItem.prototype) {
+        return item.getAsFileSystemHandle().then((fileSystemHandle: any) => fileSystemHandle.getFile())
+            .catch((error: { message: any; }) => error.message);
+    }
     const file = item.getAsFile();
     if (!file) {
         return Promise.reject(`${item} is not a File`);
@@ -185,4 +189,4 @@ async function fromFileEntry(entry: any) {
 // https://github.com/Microsoft/TypeScript/issues/3496#issuecomment-128553540
 interface FileArray extends Array<FileValue> {}
 type FileValue = FileWithPath
-    | FileArray[];
+    | FileArray[];