Add expression handling to heex-ts-mode

Add expression handling to heex-ts-mode

On the latest update of the grammar expressions were added and won't be
seen as directives anymore.

* lisp/progmodes/heex-ts-mode.el
(heex-ts--sexp-regexp): Match on expression as well.
(heex-ts--indent-rules): Indent on expression end.  (Bug#75191)
* test/lisp/progmodes/heex-ts-mode-resources/indent.erts: Add expression
indent test.

(cherry picked from commit ae2589ea7a59ac3bde19b025ba4a7968c77208d7)