[FR] Make the Position Fixed at a place for Toolbar

### Description

I want to use appflowy inside an already created list..
and also i want method so that instead of floating toolbar i want to have a toolbar which is stick to a place...
or anywhere on the page ...
(it should add height as i add new line... while inside another scrollview)

### Impact

1. Users who want to use the appflowy with their own widgets inside a list can use this featrure.

### Additional Context

_No response_