Make some page settings also configurable site wide (#182)

Adds **local** and **global** param to following front-matter vars:
- hideMeta
- ShowToc
- TocOpen
- comments

Co-authored-by: Aditya Telange <21258296+adityatelange@users.noreply.github.com>

layouts/_default/search.html

@@ -8,7 +8,7 @@
             <line x1="21" y1="21" x2="16.65" y2="16.65"></line>
         </svg>
     </h1>
-    {{- if .Params.hideMeta }}{{ else }}
+    {{- if not (.Param "hideMeta") }}
     <div class="post-meta">
         {{- if .IsTranslated -}}
         <ul class="i18n_list">