feat(react/dialogs): port upload attachments

apps/client/src/widgets/react/FormFileUpload.tsx

@@ -0,0 +1,13 @@
+interface FormFileUploadProps {
+    onChange: (files: FileList | null) => void;
+    multiple?: boolean;
+}
+
+export default function FormFileUpload({ onChange, multiple }: FormFileUploadProps) {
+    return (
+        <label class="tn-file-input tn-input-field">
+            <input type="file" class="form-control-file" multiple={multiple}
+                onChange={e => onChange((e.target as HTMLInputElement).files)} />
+        </label>
+    )
+}