[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/annotations/MultiDeclaration.fir.kt

@@ -0,0 +1,9 @@
+annotation class Ann
+
+data class Pair(val x: Int, val y: Int)
+
+fun foo(): Int {
+    @Ann val (a, b) = Pair(12, 34)
+    @Err val (c, d) = Pair(56, 78)
+    return a + b + c + d
+}