ui: content view: improve empty text

reference NS so that users get a hint where they are currently
hierarchy-wise, and clarify that we found no *accessible* snapshots,
on this level, i.e., there can be some that we just cannot see due to
only having access on lover level NS or being different owners.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

www/datastore/Content.js

@@ -278,7 +278,10 @@ Ext.define('PBS.DataStoreContent', {
 	    });
 
 	    if (!children.length) {
-		view.setEmptyText(gettext('No Snapshots found'));
+		view.setEmptyText(Ext.String.format(
+		    gettext('No accessible snapshots found in namespace {0}'),
+		    view.namespace && view.namespace !== '' ? `'${view.namespace}'`: gettext('Root'),
+		));
 	    }
 
 	    this.updateGroupNotes(view);