[New Control] Descriptions (#791)

* feat: add ColumnWrapPanel.

* feat: add Descriptions and DescriptionsItem controls

* WIP: extract a LabeledContentControl for this particular need.

* wip.

* feat: setup demo. fix various initial status issue.

* fix: fix a layout issue.

* feat: improve demo.

* feat: update demo.

* fix: remove a redundant calculation.

* feat: update per copilot feedback.

* feat: add tests, fix a calculation issue.

* feat: refactor to change the default label and value binding assignment logic.

* feat: introduce orientation.

* misc: format codes.

* feat: clarify LabelPosition property.

* feat: extract Font resources.

* revert AvatarDemo.

* feat: assign specific value to Font resources for testing.

* misc: resolve copilot comment.

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Co-authored-by: Zhang Dian <54255897+zdpcdt@users.noreply.github.com>

src/Ursa.Themes.Semi/Themes/Dark/_index.axaml

@@ -8,6 +8,7 @@
         <ResourceInclude Source="ButtonGroup.axaml" />
         <ResourceInclude Source="Clock.axaml" />
         <ResourceInclude Source="DatePicker.axaml" />
+        <ResourceInclude Source="Descriptions.axaml" />
         <ResourceInclude Source="Dialog.axaml" />
         <ResourceInclude Source="Divider.axaml" />
         <ResourceInclude Source="DualBadge.axaml" />