Fix check-boot-jars when a boot jar is provided by prebuilt

Previously, when a boot jar was provided by a java_sdk_library_import
module the check-boot-jars check failed because the file it depended on
was not available. In an incremental build the build failed due to the
file in the out directory not having a rule to generate it.

That was because the module was named prebuilt_<module>.<apex> instead
of <module>.<apex>. This was fixed by simply removing prebuilt_ prefix
from the name if it was present.

After fixing that the check-boot-jars still did not work properly
because it was expecting a jar file containing .class files but instead
was given a jar file containing .dex files which meant the check did
not work properly.

This was fixed by defining a new ApexDependency interface for use by
the apex/apex.go code to use instead of java.Dependency for generating
the androidmk entries. The *SdkLibraryImport type then implemented
those, by delegating to the implementation library.

Bug: 158304459
Bug: 159112414
Test: m check-boot-jars
      m checkbuild
	  manual inspection of the .jar file used by check-boot-jars to
	  ensure it contained .class files and not .dex files.
Change-Id: I545c5c9072dd472337d2f9b4dfdf08f53c981662
diff --git a/java/java.go b/java/java.go
index bd5f6b7..d7f09f9 100644
--- a/java/java.go
+++ b/java/java.go
@@ -496,11 +496,16 @@
 
 var _ android.OutputFileProducer = (*Module)(nil)
 
-type Dependency interface {
+// Methods that need to be implemented for a module that is added to apex java_libs property.
+type ApexDependency interface {
 	HeaderJars() android.Paths
+	ImplementationAndResourcesJars() android.Paths
+}
+
+type Dependency interface {
+	ApexDependency
 	ImplementationJars() android.Paths
 	ResourceJars() android.Paths
-	ImplementationAndResourcesJars() android.Paths
 	DexJarBuildPath() android.Path
 	DexJarInstallPath() android.Path
 	AidlIncludeDirs() android.Paths