TEIIDDES-1591: Override the secure storage default password provider

* Overrides the default displayed dialog with something altogether more
  informative.

* Adds in an help context so that help icon on the dialog points to
  the Secure Storage documentation that comes as part of eclipse.
Remove Teiid View and add Servers View to the Designer perspective

* The original Teiid View is no longer required as all its content is
  available from the servers view.

* org.teiid.designer.ui/plugin.xml
 * Adds the Servers View to the stack of the Problems View in the perspective