Add UI support for the Aria, Graphite and Material themes

[fabriciomurta]

As per this comment, the Aria theme did not support the UI mechanism and its setting were removed from the UI examples that used to let the user choose this.

This Ext.NET thread requests support for this feature on the Aria theme: C# MVC Button.UI & Button.Icon under Aria Theme will cause WebResource.axd, The resource cannot be found error

[fabriciomurta]

This issue extends also to the Graphite and Material theme (but they weren't removed from the dropdown in related examples).

[fabriciomurta]

As other themes support this UI, this is deemed an issue (defect) with Ext.NET 5.