KT-13220: Add completion for variable names

Using parameter name completion

#KT-13220 fixed

idea/idea-completion/testData/basic/common/variableNameAndType/Lateinit.kt

@@ -0,0 +1,6 @@
+
+class Foo
+
+lateinit var f<caret>
+
+// EXIST: { itemText: "foo: Foo" }

idea/idea-completion/testData/basic/common/variableNameAndType/Local.kt

@@ -0,0 +1,8 @@
+
+class Foo
+
+fun test() {
+    var f<caret>
+}
+
+// EXIST: { itemText: "foo", tailText: ": Foo (<root>)" }

idea/idea-completion/testData/basic/common/variableNameAndType/TopLevel.kt

@@ -0,0 +1,6 @@
+
+class Foo
+
+val f<caret>
+
+// EXIST: { itemText: "foo", tailText: ": Foo (<root>)" }