Support for checking loaded descriptors agains an expected txt file

compiler/testData/lazyResolve/diagnostics/dataFlow/CalleeExpression.txt

@@ -0,0 +1,7 @@
+namespace <root>
+
+internal final class C : jet.Any {
+    public final /*constructor*/ fun <init>(/*0*/ f: jet.Function0<jet.Tuple0>): C
+    internal final val f: jet.Function0<jet.Tuple0>
+}
+internal final fun test(/*0*/ e: jet.Any): jet.Tuple0

compiler/testData/lazyResolve/diagnostics/dataFlow/TupleExpression.txt

@@ -0,0 +1,7 @@
+namespace <root>
+
+internal final class C : jet.Any {
+    public final /*constructor*/ fun <init>(/*0*/ f: jet.Int): C
+    internal final val f: jet.Int
+}
+internal final fun test(/*0*/ e: jet.Any): jet.Tuple0

compiler/testData/lazyResolve/diagnostics/dataFlow/WhenSubject.txt

@@ -0,0 +1,9 @@
+namespace <root>
+
+internal final class BinOp : Expr {
+    public final /*constructor*/ fun <init>(/*0*/ operator: jet.String): BinOp
+    internal final val operator: jet.String
+}
+internal abstract trait Expr : jet.Any {
+}
+internal final fun test(/*0*/ e: Expr): jet.Tuple0