Refresh sidebars

[gadenbuie]

## bslib
- [x] Top-align toggle, sticky within layout sidebar container
- [x] Less tab-style, more button
- [x] Floats between outside sidebar when collapsed, inside sidebar when open
- [ ] Sidebar `position = "right"` as new default?

## Shiny Preset
- [ ] More padding-top in page-level sidebars
- [x] Default to background to white

[gadenbuie]

Completed in #798

[github-actions]

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