Improve components documentation

[saemideluxe]

The documentation for the components could be improved a lot by adding parts of the carbon documentation directly into the docstrings. Also, extending the widgetpreview to include more components would be nice.

• [ ] bread.layout.components.button
• [ ] bread.layout.components.content_switcher
• [ ] bread.layout.components.datatable
• [ ] bread.layout.components.forms # present on widget preview, but docstrings for widgets not complete?
• [ ] bread.layout.components.grid
• [ ] bread.layout.components.icon
• [ ] bread.layout.components.loading
• [ ] bread.layout.components.modal
• [ ] bread.layout.components.notification
• [ ] bread.layout.components.overflow_menu
• [ ] bread.layout.components.pagination
• [ ] bread.layout.components.progress_indicator
• [ ] bread.layout.components.search
• [x] bread.layout.components.shell_header # this is complicated and not very standardized anyway, ignoring
• [ ] bread.layout.components.sidenav
• [ ] bread.layout.components.tabs
• [ ] bread.layout.components.tag
• [ ] bread.layout.components.toggle
• [x] bread.layout.components.tooltip