This change updates how certain dialogs signal that they have closed, preparing the system for an upcoming framework upgrade. It is an internal cleanup affecting mobile, spreadsheet, enterprise web, and studio areas, with no expected change to day-to-day user workflows.

*: documents_spreadsheet, web_enterprise, web_studio

In owl-2, t-on will no longer be supported on components. This commit
converts the dialog-closed event to use a callback-prop based approach.