Expose API to provide expandable message in notifications

[nelango]

Expose API to provide expandable message in notifications (showInformationMessage / showWarningMessage / showErrorMessage ). The API could be something like: showInformationMessage(summaryMessage: string, fullMessage: string, ...items: string[])

Currently, if actions are present in these notification messages, the view is automatically expanded. Instead:

• minimize it and display a summary message by default
• make it expandable and display the full message exposed through API when expanded

[bpasero]

//cc @jrieken

[jrieken]

dupe of #125750?

[bpasero]

Yeah maybe, if we end up implementing the new detail option like that for notifications, an extension could use message for the brief variant and add additional content to details. Let's move into that issue, @nelango maybe comment there.