fix(ui) Fix gravatar fallbacks (#16336)

When updating Gravatar to typescript, I removed some property spreads as
they triggered typescript warnings and the propTypes didn't cover any
props that needed spreading. The onLoad and onError props were load
bearing as they are used to handle gravatar fallbacks.

Author: markstory

src/sentry/static/sentry/app/components/avatar/baseAvatar.tsx

@@ -178,6 +178,7 @@ class BaseAvatar extends React.Component<Props, State> {
           gravatarId={gravatarId}
           round={round}
           remoteSize={DEFAULT_REMOTE_SIZE}
+          {...eventProps}
         />
       );
     }

src/sentry/static/sentry/app/components/avatar/gravatar.tsx

@@ -16,6 +16,8 @@ type Props = {
    * Should avatar be round instead of a square
    */
   round?: boolean;
+  onLoad?: () => void;
+  onError?: () => void;
 };
 
 type State = {
@@ -81,9 +83,16 @@ class Gravatar extends React.Component<Props, State> {
       return null;
     }
 
-    const {round} = this.props;
+    const {round, onError, onLoad} = this.props;
 
-    return <Image round={round} src={this.buildGravatarUrl()} />;
+    return (
+      <Image
+        round={round}
+        src={this.buildGravatarUrl()}
+        onLoad={onLoad}
+        onError={onError}
+      />
+    );
   }
 }