textproc/saxon-he: Improve wrapper scripts

• make robust and put the literal string first in the script's IAM comparison so that in no case can it start with a dash
• make efficient and use Makefile's :tsc (:ts:) transform to get classpath-ready colon-separated jars list without assembling it in the script each time. Else you could avoid adding the leading colon like so: SAXON_CLASSPATH="${SAXON_CLASSPATH}${SAXON_CLASSPATH:+:}${jarfile}"
• install saxon-xquery as symlink instead of a copy
• add saxon and saxon-xquery scripts to post-stage smoke test
• bump PORTREVISION which was deferred from prior commit

PR: 286764