build: udl: combine package/compile methods
* drop old deprecated package method

(integrated from trunk branch change 0f58d61 by Todd Whiteman <toddw@activestate.com>)
build: udl: pass xpi filename to KoExt build method
* allows proper dependency management for building xpi files

(integrated from trunk branch change 043f67c by Todd Whiteman <toddw@activestate.com>)