Effects: add (de)serialization of contracts in metadata

- Introduce new definitions in descriptors.proto
- Add new corresponding values in Flags.java
- Introduce ContractSerializer and ContractDeserializer, responsible for
for conversion ContractDescription <-> ProtoBuf.Contract
- Add dependency of 'serialization' module on 'resolution' so that it
could see contracts model.

Note that here we do a lot of seemingly unnecessary hoops, which in fact
necessary to respect existing module system (in particular, to be able
to extract ContractDescription declarations from 'descriptors' module to
make them invisible from reflection)

==========
Effect System introduction: 8/18

core/descriptors.runtime/src/org/jetbrains/kotlin/load/kotlin/reflect/RuntimeModuleData.kt

@@ -36,6 +36,7 @@ import org.jetbrains.kotlin.load.kotlin.JavaClassDataFinder
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.platform.JvmBuiltIns
 import org.jetbrains.kotlin.resolve.jvm.JavaDescriptorResolver
+import org.jetbrains.kotlin.serialization.deserialization.ContractDeserializer
 import org.jetbrains.kotlin.serialization.deserialization.DeserializationComponents
 import org.jetbrains.kotlin.serialization.deserialization.DeserializationConfiguration
 import org.jetbrains.kotlin.storage.LockBasedStorageManager
@@ -82,7 +83,7 @@ class RuntimeModuleData private constructor(
             val deserializationComponentsForJava = DeserializationComponentsForJava(
                     storageManager, module, DeserializationConfiguration.Default, javaClassDataFinder,
                     binaryClassAnnotationAndConstantLoader, lazyJavaPackageFragmentProvider, notFoundClasses,
-                    RuntimeErrorReporter, LookupTracker.DO_NOTHING
+                    RuntimeErrorReporter, LookupTracker.DO_NOTHING, ContractDeserializer.DEFAULT
             )
 
             singleModuleClassResolver.resolver = javaDescriptorResolver