Changed imports semantics: imports order does not affect resolve, explicit imports have higher priority for classes

compiler/testData/diagnostics/tests/imports/ExplicitImportsAmbiguity.kt

@@ -0,0 +1,17 @@
+// FILE: a.kt
+package a
+
+class X
+
+// FILE: b.kt
+package b
+
+class X
+
+// FILE: c.kt
+package c
+
+import a.X
+import b.X
+
+class Y : <!UNRESOLVED_REFERENCE!>X<!>