Rewritten KDoc-link resolve and completion to work more reasonably

idea/testData/kdoc/resolve/ExtensionVal.kt

@@ -0,0 +1,14 @@
+package a
+
+class B {
+    /**
+     * [a.B.<caret>extVal]
+     */
+    fun member() {
+    }
+}
+
+val B.extVal: String
+    get() = ""
+
+// REF: (for B in a).extVal