feat(navbar): navbar link icon item (#781)

* chore: extract link code to a partial

* feat(navbar): item icon

* chore: generate

* docs: add configuration

* review

Co-authored-by: Xin <5097752+imfing@users.noreply.github.com>

* chore: generate

* chore: add examples

* chore: showcase

---------

Co-authored-by: Xin <5097752+imfing@users.noreply.github.com>

exampleSite/hugo.yaml

@@ -85,6 +85,9 @@ menu:
       name: Showcase
       pageRef: /showcase
       weight: 5
+      params:
+        type: link
+        icon: collection
     - name: Search
       weight: 6
       params:
@@ -98,6 +101,9 @@ menu:
       name: Development ↗
       url: https://imfing.github.io/hextra/versions/latest/
       parent: versions
+      params:
+        type: link
+        icon: beaker
     - identifier: v0.9
       name: v0.9 ↗
       url: https://imfing.github.io/hextra/versions/v0.9/