Permissions XML file for java_sdk_library is mutated for APEX

This change fixes a regression that was introduced with
I597bccbb177b6b6320c3a3edeff467243230d384. With the change, the content
of the permissions XML file for a java_sdk_library was determined before
the java_sdk_library is mutated for an APEX. As a result, the file path
to the implementation jar library was always set to
/system/framework/*.jar regardless of whether the java_sdk_library is
part of an APEX or not.

This change fixes the problem, by creating the permissions XML file via
a new module type. The content of the xml file is determined after the
xml file is mutated for APEXes.

Bug: 149600642
Test: m

Change-Id: Id21f8d8285df49b0b3be1daf0f101f2bc978eeb0
diff --git a/apex/apex_test.go b/apex/apex_test.go
index 0420586..c08a11e 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -3488,9 +3488,8 @@
 		"etc/permissions/foo.xml",
 	})
 	// Permission XML should point to the activated path of impl jar of java_sdk_library
-	sdkLibrary := ctx.ModuleForTests("foo", "android_common_myapex").Module().(*java.SdkLibrary)
-	xml := sdkLibrary.XmlPermissionsFileContent()
-	ensureContains(t, xml, `<library name="foo" file="/apex/myapex/javalib/foo.jar"`)
+	sdkLibrary := ctx.ModuleForTests("foo.xml", "android_common_myapex").Rule("java_sdk_xml")
+	ensureContains(t, sdkLibrary.RuleParams.Command, `<library name=\"foo\" file=\"/apex/myapex/javalib/foo.jar\"`)
 }
 
 func TestCompatConfig(t *testing.T) {