Add test for checking ambiguity for root package and the same package

compiler/testData/diagnostics/tests/scopes/AmbiguityBetweenRootAndPackage.kt

@@ -0,0 +1,12 @@
+// FILE: checkAmbiguityBetweenRootAndPackage.kt
+package test
+
+val t = <!OVERLOAD_RESOLUTION_AMBIGUITY!>testFun()<!>
+
+// FILE: checkAmbiguityBetweenRootAndPackageRoot.kt
+fun testFun() = 12
+
+// FILE: checkAmbiguityBetweenRootAndPackageTest.kt
+package test
+
+fun testFun() = 12

compiler/testData/lazyResolve/diagnostics/overload/AmbiguityBetweenRootAndPackage.txt

@@ -0,0 +1,9 @@
+namespace <root>
+
+// <namespace name="test">
+namespace test
+
+internal final val t: [ERROR : Type for testFun()]
+internal final fun testFun(): jet.Int
+// </namespace name="test">
+internal final fun testFun(): jet.Int