MM-55468 Ensure custom status emojis exist (#25501)

* MM-55468 Ensure custom status emojis exist

* Fix plugin API unit test

* Print underlying error as detailed error message

* Convert CustomStatusModal tests to React Testing Library and improve a11y

* Don't suggest custom statuses with non-existent emojis

* Silence test error by providing fake translation strings

webapp/channels/src/tests/react_testing_utils.tsx

@@ -23,6 +23,7 @@ export * from '@testing-library/react';
 export {userEvent};
 
 export type FullContextOptions = {
+    intlMessages?: Record<string, string>;
     locale?: string;
     useMockedStore?: boolean;
 }
@@ -33,6 +34,7 @@ export const renderWithContext = (
     partialOptions?: FullContextOptions,
 ) => {
     const options = {
+        intlMessages: partialOptions?.intlMessages,
         locale: partialOptions?.locale ?? 'en',
         useMockedStore: partialOptions?.useMockedStore ?? false,
     };
@@ -55,6 +57,7 @@ export const renderWithContext = (
                 <Router history={renderState.history}>
                     <IntlProvider
                         locale={renderState.options.locale}
+                        messages={renderState.options.intlMessages}
                     >
                         <WebSocketContext.Provider value={WebSocketClient}>
                             {props.children}