Load definitions of symbols from .kotlin_metadata files

Extract AbstractDeserializedPackageFragmentProvider out of
JvmBuiltInsPackageFragmentProvider and implement it a little bit differently in
MetadataPackageFragmentProvider. The main difference is in how the package
fragment scope is constructed: for built-ins, it's just a single scope that
loads everything from one protobuf message. For metadata, package scope can
consist of many files, some of which store information about classes and others
are similar to package parts on JVM, so a ChainedMemberScope instance is
created.

Introduce a bunch of interfaces/methods to deliver the needed behavior to the
'deserialization' module which is not JVM-specific and does not depend on the
compiler code: MetadataFinderFactory,
PackagePartProvider#findMetadataPackageParts, KotlinMetadataFinder#findMetadata.
Note that these declarations are currently only implemented in the compiler; no
metadata package parts/fragments will be found in IDE or reflection

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/resolve/IDEPackagePartProvider.kt

@@ -18,14 +18,17 @@ package org.jetbrains.kotlin.idea.caches.resolve
 
 import com.intellij.psi.search.GlobalSearchScope
 import com.intellij.util.indexing.FileBasedIndex
-import org.jetbrains.kotlin.idea.vfilefinder.KotlinModuleMappingIndex
 import org.jetbrains.kotlin.descriptors.PackagePartProvider
+import org.jetbrains.kotlin.idea.vfilefinder.KotlinModuleMappingIndex
 import org.jetbrains.kotlin.load.kotlin.PackageParts
 
 class IDEPackagePartProvider(val scope: GlobalSearchScope) : PackagePartProvider {
+    override fun findPackageParts(packageFqName: String): List<String> =
+            getPackageParts(packageFqName).flatMap(PackageParts::parts).distinct()
 
-    override fun findPackageParts(packageFqName: String): List<String> {
-        val values: MutableList<PackageParts> = FileBasedIndex.getInstance().getValues(KotlinModuleMappingIndex.KEY, packageFqName, scope)
-        return values.flatMap { it.parts }.distinct()
-    }
-}
+    override fun findMetadataPackageParts(packageFqName: String): List<String> =
+            getPackageParts(packageFqName).flatMap(PackageParts::metadataParts).distinct()
+
+    private fun getPackageParts(packageFqName: String): MutableList<PackageParts> =
+            FileBasedIndex.getInstance().getValues(KotlinModuleMappingIndex.KEY, packageFqName, scope)
+}

idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/classFile/DeserializerForClassfileDecompiler.kt

@@ -116,6 +116,9 @@ class DirectoryBasedClassFinder(
         return null
     }
 
+    // TODO
+    override fun findMetadata(classId: ClassId): InputStream? = null
+
     // TODO: load built-ins from packageDirectory?
     override fun findBuiltInsData(packageFqName: FqName): InputStream? = null
 }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/vfilefinder/fileFinders.kt

@@ -56,6 +56,9 @@ class JsIDEVirtualFileFinder(private val scope: GlobalSearchScope) : JsVirtualFi
 }
 
 class JvmIDEVirtualFileFinder(private val scope: GlobalSearchScope) : VirtualFileKotlinClassFinder(), JvmVirtualFileFinder {
+    // TODO
+    override fun findMetadata(classId: ClassId): InputStream? = null
+
     // TODO: load built-ins metadata from scope
     override fun findBuiltInsData(packageFqName: FqName): InputStream? = null