react-intl: change the FormattedMessage tagName prop to accept any ReactType (#31906)

In the react-intl source the prop is defined as follows:

    tagName: PropTypes.oneOfType([PropTypes.string, PropTypes.element])

But it's actually passed straight to React.createElement(tagName, …),
so any type that is accepted by createElement should be allowed here.

It is useful to allow passing custom components to FormattedMessage,
for example when you use styled components, eg.

    const FancyHeading = styled('h1')`font-size: 32px`;
    <FormattedMessage … tagName={FancyHeading} />

types/react-intl/index.d.ts

@@ -146,7 +146,7 @@ declare namespace ReactIntl {
 
         interface Props extends MessageDescriptor {
             values?: {[key: string]: MessageValue | JSX.Element};
-            tagName?: string;
+            tagName?: React.ReactType;
             children?: (...formattedMessage: Array<string | JSX.Element>) => React.ReactNode;
         }
     }

types/react-intl/react-intl-tests.tsx

@@ -156,6 +156,13 @@ class SomeComponent extends React.Component<SomeComponentProps & InjectedIntlPro
                 values={{ blank: null, empty: undefined }}
                 tagName="div" />
 
+            <FormattedMessage
+                id="test"
+                description="Test"
+                defaultMessage="Hi {blank} and {empty}!"
+                values={{ blank: null, empty: undefined }}
+                tagName={({ children }) => <div>{children}</div>} />
+
             <FormattedMessage
                 id="test"
                 description="Test"