Refactor user interface for plugin tiddlers

* Refactored control panel “Plugins” tab to make the elements more
reusable
* Refactored the display of plugin tiddlers to use the same format as
the control panel (as suggested, I think by @danielo515), adding the
shadow tiddler listing as an overridable extension tab
* Added a new tab in the “More” sidebar providing quick access to all
installed plugins

core/ui/ViewTemplate/plugin.tid

@@ -2,7 +2,11 @@ title: $:/core/ui/ViewTemplate/plugin
 tags: $:/tags/ViewTemplate
 
 <$list filter="[all[current]has[plugin-type]] -[all[current]field:plugin-type[import]]">
-
-{{||$:/core/ui/TiddlerInfo/Advanced/PluginInfo}}
-
+<$set name="plugin-type" value={{!!plugin-type}}>
+<$set name="default-popup-state" value="yes">
+<$set name="qualified-state" value=<<qualify "$:/state/plugin-info">>>
+{{||$:/core/ui/Components/plugin-info}}
+</$set>
+</$set>
+</$set>
 </$list>