Merge the right sidebar logic into the workbench. this can simplify our logic.
Previously we had 3 modules
* workbench
* right-sidebar (Control sidebar open&close)
* multi-tab-sidebar (Control tabs)
Now everything is managed in Workbench.
# Behavioral changes
The sidebar button is always visible and can be opened at any time.
If there is no content to display, will be `No Selection`

Elements in the sidebar can now be defined as`unmountOnInactive=false`. Inactive sidebars are marked with `display: none` but not unmount, so the `ChatPanel` can always remain in the DOM and user input will be retained even if the sidebar is closed.