[LL FIR] add test which checks reference shortening for the whole file

^KT-57966

analysis/analysis-api/testData/components/referenceShortener/referenceShortenerWholeFile/fileWithMultipleDeclarations.kt

@@ -0,0 +1,17 @@
+class A {
+    abstract class B {
+        abstract val b: A.B
+    }
+}
+
+class C {
+    abstract class D {
+        companion object {
+            fun foo() {}
+        }
+
+        init {
+            C.D.Companion.foo()
+        }
+    }
+}

analysis/analysis-api/testData/components/referenceShortener/referenceShortenerWholeFile/fileWithMultipleDeclarations.txt

@@ -0,0 +1,2 @@
+[type] A.B
+[qualifier] C.D.Companion.foo()