Code refactoring (#2785)

* chore: pretty theme menu in sidebar

* refactor: renaming component templates

* refactor: create custom `a-statistic` component

* fix: display button text only on large screens

* chore: remove loading background in overview page

* fix: show `Version` text when xray version is unknown

web/html/xui/xray.html

@@ -788,9 +788,9 @@
     </a-layout>
   </a-layout>
 {{template "js" .}}
-{{template "component/themeSwitcher" .}}
-{{template "component/sortableTable" .}}
-{{template "component/setting"}}
+{{template "component/aThemeSwitch" .}}
+{{template "component/aTableSortable" .}}
+{{template "component/aSettingListItem" .}}
 {{template "ruleModal"}}
 {{template "outModal"}}
 {{template "reverseModal"}}