feat: migrate social sharing config to Hugo Cascade

Just add `share: false` to page front matter or via Hugo Cascades to disable the page sharer at the bottom of pages.

See https://discord.com/channels/722225264733716590/742863504515793149/956507676806877235
See #2601

starters/blog/config/_default/config.yaml

@@ -19,6 +19,7 @@ cascade:
     commentable: true
     show_related: true
     show_breadcrumb: true
+    share: true
     header:
       navbar:
         enable: false

wowchemy/layouts/partials/components/page_sharer.html

@@ -1,4 +1,4 @@
-{{ if and site.Params.sharing (ne .Params.share false) }}
+{{ if ne .Params.share false }}
 <div class="share-box">
   <ul class="share">
     {{ range where site.Data.page_sharer.buttons "enable" true }}