JS: serialize .kjsm package-wise, adapt decompiler & stub builder

Instead of multiple .kjsm files for different classes and .kotlin_string_table,
.kotlin_file_table, .kotlin_classes files for each package, serialize the
contents of each package to a single foo/bar/baz/baz.kjsm file. The short name
of the file is the last segment in the FQ name of the package, or
"root-package" if the package is root.

There are two main reasons for this change:
1) Such structure takes less space, is more IO-friendly and will not cause
   multiple exceptions as the old one, where we sometimes tried to read
   non-existing files
2) This is exactly the same format that is used to serialize built-in
   declarations (.kotlin_builtins) at the moment, which will allow us to reuse
   some code

Also write a separate Header protobuf message to the beginning of the .kjsm
file. This will be used as arguments of the kotlin.Metadata annotation are used
in the JVM-specific parts of the compiler: to be able to provide some general
information about the binary file without parsing the whole protobuf data.

This commit breaks decompiled text & stub builder consistency tests. This is OK
because they're removed in a future commit.

Fixes EA-79605, EA-81947, EA-84277 and maybe EA-86787

 #KT-10894 Fixed
 #KT-14124 Fixed
 #KT-15755 Fixed

compiler/util/src/org/jetbrains/kotlin/utils/KotlinJavascriptMetadataUtils.kt

@@ -17,7 +17,9 @@
 package org.jetbrains.kotlin.utils
 
 import org.jetbrains.kotlin.serialization.deserialization.BinaryVersion
+import java.io.DataInputStream
 import java.io.File
+import java.io.InputStream
 import javax.xml.bind.DatatypeConverter.parseBase64Binary
 import javax.xml.bind.DatatypeConverter.printBase64Binary
 
@@ -31,10 +33,21 @@ class JsBinaryVersion(vararg numbers: Int) : BinaryVersion(*numbers) {
 
     companion object {
         @JvmField
-        val INSTANCE = JsBinaryVersion(0, 7, 0)
+        val INSTANCE = JsBinaryVersion(0, 8, 0)
 
         @JvmField
         val INVALID_VERSION = JsBinaryVersion()
+
+        fun readFrom(stream: InputStream): JsBinaryVersion {
+            val dataInput = DataInputStream(stream)
+            val size = dataInput.readInt()
+
+            // We assume here that the version will always have 3 components. This is needed to prevent reading an unpredictable amount
+            // of integers from old .kjsm files (pre-1.1) because they did not have the version in the beginning
+            if (size != INSTANCE.toArray().size) return INVALID_VERSION
+
+            return JsBinaryVersion(*(1..size).map { dataInput.readInt() }.toIntArray())
+        }
     }
 }