Improve handling of unsupported macros added to comments

Summary

In Confluence, when a comment has unsupported content (I.E. macros that cannot be added manually; macros added to them prior to migration from Server to Cloud), the following error message is displayed:

This content cannot be displayed as it was created in a legacy version of Confluence and is unsupported.

This can happen via the following scenarios:

• If we use the Confluence Cloud API to update content and point it toward the ID of a comment, manually adding a macro that is only available in pages.
• If Confluence is migrated from Server, containing macros that cannot be added in comments only in Cloud.

Suggestion

Due to this being a generic message that also avoids the comment's content to be fetched, this is a suggestion to:

• Improve the error message stating that there is unsupported content in the comment and what is the unsupported content.
• Provide a method for the user to get the comment's content.
• Block the API to add a macro that is not supported in comments.