Rename source set "descriptor.loader.java" -> "descriptors.jvm"

The new name is more convenient and precise because this module is no
longer only about loading declarations from Java, it also contains
implementation of loading Kotlin declarations from .class files, as well
as type mapping abstractions, JVM ABI specifications, etc.

libraries/tools/kotlin-reflect/build.gradle

@@ -87,7 +87,7 @@ task reflectShadowJar(type: ShadowJar) {
     manifestAttributes(manifest, project, 'Main')
 
     from (sourceSets.main.output)
-    from ("${core}/descriptor.loader.java/src") {
+    from ("${core}/descriptors.jvm/src") {
         include 'META-INF/services/**'
     }
     from ("${core}/deserialization/src") {
@@ -141,8 +141,8 @@ task relocateCoreSources(type: Copy) {
         delete(relocatedCoreSrc)
     }
 
-    from "${core}/descriptor.loader.java/src/${commonPackage}"
     from "${core}/descriptors/src/${commonPackage}"
+    from "${core}/descriptors.jvm/src/${commonPackage}"
     from "${core}/descriptors.runtime/src/${commonPackage}"
     from "${core}/deserialization/src/${commonPackage}"
     from "${core}/util.runtime/src/${commonPackage}"