Chase editors/emacs update to 29.4

- Bump Emacs version in Mk/Uses/emacs.mk to update version-specific
  paths
- Bump PORTREVISION of ports with USES=emacs.  This is required for two
  reasons.  Emacs lisp files need to be byte compiled for the new Emacs
  version, and files installed under, e.g., EMACS_VERSION_SITE_LISPDIR
  need to be relocated.

Reviewed by:	ashish, yasu
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D45705