Effects: add test on (de)serialization of contracts

- Add ContractDescriptorRenderer
- Add option to dump function contracts in DescriptorRendererOptions
- Add parsing of LANGUAGE_VERSION directive in AbstractLoadJava
- Add tests on serialization-deserializaton identity of contracts

==========
Introduction of EffectSystem: 13/18

compiler/testData/loadJava/compiledKotlinWithStdlib/contracts/mutualRecursion.kt

@@ -0,0 +1,20 @@
+// LANGUAGE_VERSION: 1.3
+@file:Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+
+package test
+
+import kotlin.internal.contracts.*
+
+fun foo(x: Any?): Boolean {
+    contract {
+        returns() implies (x is String)
+    }
+    return bar(x)
+}
+
+fun bar(x: Any?): Boolean {
+    contract {
+        returns() implies (x is Int)
+    }
+    return foo(x)
+}