Effects: add diagnostic tests on contracts

- Make AbstractDiagnosticsTest dump function contracts
- Add diagnostics tests on parsing contracts
- Add diagnostics tests on smartcats in presence of functions with
contracts
- Add diagnostics tests on initialization and flow in presence of
in-place called lambdas

==========
Introduction of EffectSystem: 16/18

compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nestedTryCatchs.kt

@@ -0,0 +1,46 @@
+// !LANGUAGE: +CallsInPlaceEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.internal.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun innerComputation(): Int = 42
+fun outerComputation(): Int = 52
+
+fun innerTryCatchInitializes() {
+    val x: Int
+
+    try {
+        myRun {
+            try {
+                x = innerComputation()
+                x.inc()
+            }
+            catch (e: java.lang.Exception) {
+                // Potential reassignment because x.inc() could threw
+                <!VAL_REASSIGNMENT!>x<!> = 42
+                x.inc()
+            }
+        }
+        // Can get here only when inlined lambda exited properly, i.e. x is initialized
+        x.inc()
+        outerComputation()
+
+    } catch (e: java.lang.Exception) {
+        // Can get here if innerComputation() threw an exception that wasn't catched by the inner catch (x is not initialized)
+        // OR if outerComputation() threw an exception (x is initialized because we reach outer computation only when inner finished ok)
+        // So, x=I? here
+        <!UNINITIALIZED_VARIABLE!>x<!>.inc()
+
+        // Potential reasignment
+        x = 42
+    }
+    // Here x=I because outer try-catch either exited normally (x=I) or catched exception (x=I, with reassingment, though)
+    x.inc()
+}