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/unreachableCode.kt

@@ -0,0 +1,16 @@
+// !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 throwInLambda(): Int {
+    <!UNREACHABLE_CODE!>val <!UNUSED_VARIABLE!>x<!> =<!> myRun { throw java.lang.IllegalArgumentException(); <!UNREACHABLE_CODE!>42<!> }
+    <!UNREACHABLE_CODE!>return x<!>
+}