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/embedding.kt

@@ -0,0 +1,33 @@
+// LANGUAGE_VERSION: 1.3
+@file:Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+
+package test
+
+import kotlin.internal.contracts.*
+
+// this tests specifically use primitive condition (predicate/value) as the
+// first argument of sequence, so that it would be optimized and embedded into message
+
+fun embedVariable(x: Any, b: Boolean) {
+    contract {
+        returns() implies (b && x is String)
+    }
+}
+
+fun embedInstancePredicate(x: Any, y: Any?) {
+    contract {
+        returns() implies (x is String && y is String)
+    }
+}
+
+fun embedNullCheckPredicate(x: Any?, y: Int?) {
+    contract {
+        returns() implies (y != null && x is String)
+    }
+}
+
+fun Boolean.embedReceiverReference(b: Boolean) {
+    contract {
+        returns() implies (!this@embedReceiverReference && b)
+    }
+}