I'd like to add positioning to the Toast API

Toast component is currently fixed to the bottom-right. Some users may need/want the placement of the Toast to be in a different location. Also a per-Toast override could/would be useful.

If this is good I can create a PR
[Branch](https://github.com/gitpush-gitpaid/kumo/tree/feat/toast-position)

position="top-right"

position="top-center"

Start by inspecting the existing Toast component and its public API, then compare the proposed changes in the linked feat/toast-position branch. Verify that supported placement options and a per-Toast override behave as shown for top-right and top-center positions.

Written by the indexing model from the issue text.