Introduce a concept of "non-urgent" toasts

This is somewhat expected to be temporary.

src/@types/common.ts

@@ -14,7 +14,11 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+import { JSXElementConstructor } from "react";
+
 // Based on https://stackoverflow.com/a/53229857/3532235
 export type Without<T, U> = {[P in Exclude<keyof T, keyof U>] ? : never};
 export type XOR<T, U> = (T | U) extends object ? (Without<T, U> & U) | (Without<U, T> & T) : T | U;
 export type Writeable<T> = { -readonly [P in keyof T]: T[P] };
+
+export type ComponentClass = keyof JSX.IntrinsicElements | JSXElementConstructor<any>;