feat(picker): storybook - expanded and improved chromatic template

Expands the Chromatic-only template in Storybook to increase coverage
of different options.

Organizes the stories into sections using the formatting and typography
previously established with Action button. States in each section are
based on the grid of options in the Desktop S2 design Figma, with some
additions such as the loading state. And the Switch examples from the
existing template.

Removes the "Open" story which is now covered in the Chromatic template.

Adds missing icon (to left of value/placeholder text) option to
Storybook, along with VRT coverage.

Improves display of Popover within these different contexts; fixes how
it is aligned on the side label example. Changes the side label example
to use flex row instead of using inline-block which could wrap as the
screen shrunk.

=== Other fixes and additions ===

- Adds aria-labelledby and unique ids to make sure the label is associated
  with the Picker.
- Includes downstate dimension capture
- Popover does not show when in the loading state (per design feedback)
- Makes sure HelpText appears below the Picker when using side label, by
  adjusting its wrapper markup.
- Adds conditional controls to disabled and loading states, per the PR
  feedback that disabled + loading should not be a possible combo.

Author: jawinn

components/picker/metadata/picker.yml

@@ -13,7 +13,8 @@ sections:
       - The mod custom property `--mod-line-height-100` has been renamed to `--mod-button-line-height`.
       - The mod custom property `--mod-sans-font-family-stack` has been renamed to `--mod-button-font-family`.
       - The mod custom property `--mod-animation-duration-100` has been renamed to `--mod-button-animation-duration`.
-      - The deprecated mod custom property `--mod-picker-spacing-text-to-alert-icon-inline-start` was removed. This was replaced with `--mod-picker-spacing-text-to-alert-icon-inline-start`.
+      - The mod custom property `--mod-picker-spacing-text-to-alert-icon-inline-start` has been renamed to `--mod-picker-spacing-text-to-icon-inline-end`. This removed the fallback that was marked as deprecated in a previous version.
+      - The mod custom property `--mod-picker-spacing-text-to-icon` has been removed. Use `--mod-picker-spacing-text-to-icon-inline-end` for the spacing between text and visual (indicator or disclosure), or `--mod-picker-spacing-starting-icon-to-text` for the space between the optional workflow icon and the text.
 
       ### Versions prior to 8.0
       #### Component renamed