Toaster 5.0 changes

Toaster functionality remains the same in in Blueprint v4, but there are some name changes. As part of the effort to drop the "I" prefix from all interface names, IToaster is now simply Toaster. Toaster, which implements this interface in v3, is now OverlayToaster in v4. This more explicit name signifies that it is a certain kind of toaster, one that presents the toast messages in an overlay on top of other parts of the application (for now, it is the only available toaster implementation).

Here is the migration you can do in v3 before upgrading to v4 (these type aliases are available since @blueprintjs/core v3.44.0):

• Toaster -> OverlayToaster
• IToasterProps -> OverlayToasterProps

Finally, when you actually bump to v4, you will need to do one last rename:

• IToaster -> Toaster