Support java_sdk_library as java_libs of apex

When a java_sdk_library module is added, both impl jar and permission
xml files are packaged together.

For example, when a java_sdk_library "foo" is listed, following two
entries will be in an APEX package.

/javalibs/foo.jar
/etc/permissions/foo.xml

Bug: 145474221
Test: m com.android.cronet
      deapexer list com.android.cronet.apex

Change-Id: If5883c02255e9309f20810b1532d3fbe73bf4e95

java/java.go

@@ -426,10 +426,6 @@ func (j *Module) OutputFiles(tag string) (android.Paths, error) {
 	}
 }
 
-func (j *Module) DexJarFile() android.Path {
-	return j.dexJarFile
-}
-
 var _ android.OutputFileProducer = (*Module)(nil)
 
 type Dependency interface {