openExternalLink returns a { opened: boolean | null } result (#7273)

* Add a response type for openExternalLink that returns a boolean opened value

* updating the documentation to include the null case for older discord clients

* doc update

docs/developer_tools/Embedded_App_SDK.mdx

@@ -524,7 +524,7 @@ No scopes required
 #### Signature
 
 <Monospace>
-openExternalLink(args: [OpenExternalLinkRequest](#DOCS_DEVELOPER_TOOLS_EMBEDDED_APP_SDK/openexternallinkrequest)): Promise\<void\>
+openExternalLink(args: [OpenExternalLinkRequest](#DOCS_DEVELOPER_TOOLS_EMBEDDED_APP_SDK/openexternallinkrequest)): Promise\<[OpenExternalLinkResponse](#DOCS_DEVELOPER_TOOLS_EMBEDDED_APP_SDK/openexternallinkresponse)\>
 </Monospace>
 
 #### Usage
@@ -1335,6 +1335,15 @@ No scopes required
 |----------|--------|
 | url      | string |
 
+#### OpenExternalLinkResponse
+
+> warn
+> `{ opened: null }` is returned on Discord clients before December 2024 that do not report the open link result.
+
+| Property | Type            |
+|----------|-----------------|
+| opened   | boolean \| null |
+
 #### OpenInviteDialogRequest
 
 | Property | Type   |