[LSC] Add LOCAL_LICENSE_KINDS to build/soong

Added SPDX-license-identifier-Apache-2.0 to:
  java/core-libraries/Android.bp
  mk2rbc/Android.bp

Bug: 68860345
Bug: 151177513
Bug: 151953481

Test: m all

Exempt-From-Owner-Approval: janitorial work
Change-Id: Iaf8546fc945b04b71cd5cb1c7c16a9e15f608d02

java/core-libraries/Android.bp

@@ -24,6 +24,10 @@
 // core libraries.
 //
 // Don't use this directly, use "sdk_version: core_current".
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_library {
     name: "core.current.stubs",
     visibility: ["//visibility:public"],