Add KtUserType as completion type

Author: DonnieWest

server/src/main/kotlin/org/javacs/kt/completion/Completions.kt

@@ -244,6 +244,7 @@ private fun completableElement(file: CompiledFile, cursor: Int): KtElement? {
             // package x.y.?
             ?: el.findParent<KtPackageDirective>()
             // :?
+            ?: el as? KtUserType
             ?: el.parent as? KtTypeElement
             // .?
             ?: el as? KtQualifiedExpression