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/dsl/useBeforeDeclaration.txt

@@ -0,0 +1,6 @@
+package
+
+public fun isString(/*0*/ x: kotlin.Any?): kotlin.Boolean
+    Returns(TRUE) -> x is String
+
+public fun test(/*0*/ x: kotlin.Any?): kotlin.Unit