Add support for the Sundanese script (bug#55686)

Add support for the Sundanese script (bug#55686)

* lisp/language/indonesian.el ("Sundanese"): New language environment.
Add composition rules for Sundanese.  Add sample text and input
method.
Improve composition rules for Balinese and Javanese.
* lisp/international/fontset.el (script-representative-chars)
(setup-default-fontset): Support Sundanese.
* lisp/leim/quail/indonesian.el ("sundanese"): New input method.

* etc/HELLO: Add a Sundanese greeting.
* etc/NEWS: Announce the new language environment and its
input method.