FIR: report ambiguity-like errors in type resolve

compiler/testData/diagnostics/tests/imports/NestedClassClash.fir.kt

@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: a.kt
+package a
+
+class A {
+    class B
+}
+
+// FILE: b.kt
+package a
+
+class D {
+    class B
+}
+
+// FILE: c.kt
+import a.A.<!CONFLICTING_IMPORT!>B<!>
+import a.D.<!CONFLICTING_IMPORT!>B<!>
+
+fun test(b: <!OVERLOAD_RESOLUTION_AMBIGUITY!>B<!>) {
+    <!UNRESOLVED_REFERENCE!>B<!>()
+}
+
+// FILE: d.kt
+import a.A.*
+import a.D.*
+
+// todo ambiguvity here
+fun test2(b: <!OVERLOAD_RESOLUTION_AMBIGUITY!>B<!>) {
+    <!UNRESOLVED_REFERENCE!>B<!>()
+}