Add span wrapper around button caption text

Reasons:
- can show or hide the button text with CSS (assuming
  tv-config-toolbar-text is yes).
- can have different looking buttons in the page controls versus the
  view toolbar, etc
- more flexibility styling the button appearance, for example you
  can change the text size compared to the icon size
- button appearance is more themeable

core/ui/ViewToolbar/permaview.tid

@@ -8,6 +8,6 @@ description: {{$:/language/Buttons/Permaview/Hint}}
 {{$:/core/images/permaview-button}}
 </$list>
 <$list filter="[<tv-config-toolbar-text>prefix[yes]]">
-<$text text={{$:/language/Buttons/Permaview/Caption}}/>
+<span class="tc-btn-text"><$text text={{$:/language/Buttons/Permaview/Caption}}/></span>
 </$list>
 </$button>