Re-organizing the component gallery supporting files

[gadenbuie]

Convert to new structure

Display messages

• display-messages/modal.qmd
• display-messages/notifications.qmd
• display-messages/progress-bar.qmd
• display-messages/tooltips.qmd

Outputs

• outputs/data-grid.qmd
• outputs/datatable.qmd
• outputs/image.qmd
• outputs/map-ipyleaflet.qmd
• outputs/plot-matplotlib.qmd
• outputs/plot-plotly.qmd
• outputs/plot-seaborn.qmd
• outputs/text.qmd
• outputs/ui.qmd
• outputs/value-box.qmd
• outputs/verbatim-text.qmd

Inputs

• inputs/action-button.qmd
• inputs/action-link.qmd
• inputs/checkbox-group.qmd
• inputs/checkbox.qmd
• inputs/date-range-selector.qmd
• inputs/date-selector.qmd
• inputs/numeric-input.qmd
• inputs/password-field.qmd
• inputs/radio-buttons.qmd
• inputs/select-multiple.qmd
• inputs/select-single.qmd
• inputs/selectize-multiple.qmd
• inputs/selectize-single.qmd
• inputs/slider-range.qmd
• inputs/slider.qmd
• inputs/switch.qmd
• inputs/text-area.qmd
• inputs/text-box.qmd

[gadenbuie]

I'm going to stop this PR here and merge into express/component-gallery so that we can more easily distribute the work of rewriting the Express apps. Those PR should also merge into express/component-gallery and then when we're ready we'll merge that branch into main.