[feat]: Create `<pf-list>` element

[zeroedin]

Create <pf-list> element

Reference: List

Notes to developer:

Possible API:

Default (Unordered)

<pf-list>
  <pf-list-item icon="down-arrow" icon-set="patternfly">First Item</pf-list-item>
  <pf-list-item>Second Item</pf-list-item>
  <pf-list-item>Third Item</pf-list-item>
</pf-list>

Ordered

<pf-list ordered>
  <pf-list-item icon="user" icon-set="patternfly">First Item</pf-list-item>
  <pf-list-item>Second Item</pf-list-item>
  <pf-list-item>Third Item</pf-list-item>
</pf-list>

Plain or Ruled

<pf-list variant="plain | horizontal-rule">
  <pf-list-item icon="user" icon-set="patternfly">First Item</pf-list-item>
  <pf-list-item>Second Item</pf-list-item>
  <pf-list-item>Third Item</pf-list-item>
</pf-list>

Horizontal

<pf-list orientation="horizontal">
  <pf-list-item icon="user" icon-set="patternfly">First Item</pf-list-item>
  <pf-list-item>Second Item</pf-list-item>
  <pf-list-item>Third Item</pf-list-item>
</pf-list>

Icon size (using slotted icons)

<pf-list>
  <pf-list-item>
     <pf-icon slot="icon" icon="user" set="patternfly" size="lg"></pf-icon>
     First Item
  </pf-list-item>
  <pf-list-item>Second Item</pf-list-item>
  <pf-list-item>Third Item</pf-list-item>
</pf-list>

[bennypowers]

Covered by #3004 (PFv6 CSS utility stylesheet) -- list is better implemented as CSS classes than a custom element.