[core] fix Toaster type backcompat, better OverlayToaster docs

[adidahiya]

Fixes a regression in the Toaster type. Previously, this was assignable to the type of the whole class component, which includes more methods than simply ToasterInstance.

See https://github.com/palantir/blueprint/pull/6146/files#r1195378467

[adidahiya]

[core] fix: backwards-compatibility of Toaster type

Build artifact links for this commit: documentation | landing | table | demo

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[adidahiya]

Here's a demo of the difference between the old type and the new (fixed for backcompat) type:

old

new:

[adidahiya]

adjust type

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[adidahiya]

Here's what Toaster looked like before the OverlayToaster change: https://github.com/palantir/blueprint/blob/aa89a2e6fe54ae5e8935ec0602d6abb207c5c3c1/packages/core/src/components/toast/toaster.tsx

[adidahiya]

6b5d423 was still problematic and had this compatibility issue:

Type 'AbstractPureComponent2<OverlayToasterProps, {}, {}> & ToasterInstance' is missing the following properties from type 'OverlayToaster': toastId, isNewToastKey, dismissIfAtLimit, renderToast, and 4 more.ts(2322)

the correct fix is to use the simplest type alias: type Toaster = OverlayToaster 🤦🏽

[adidahiya]

adjust type again, add regresison test

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[adidahiya]

distinguish between ref callbacks and objects

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[adidahiya]

fix code example, add one test

Build artifact links for this commit: documentation | landing | table | demo

This is an automated comment from the deploy-preview CircleCI job.