runtime(plsql): move fold option from syntax to filetype plugin

closes: #16838

Co-authored-by: Konfekt <Konfekt@users.noreply.github.com>
Signed-off-by: Lee Lindley <lee.lindley@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/ftplugin/plsql.vim

@@ -0,0 +1,17 @@
+" Vim ftplugin file
+" Language: Oracle Procedural SQL (PL/SQL)
+" Maintainer: Lee Lindley (lee dot lindley at gmail dot com)
+" Previous Maintainer: Jeff Lanzarotta (jefflanzarotta at yahoo dot com)
+" Previous Maintainer: C. Laurence Gonsalves (clgonsal@kami.com)
+" URL: https://github.com/lee-lindley/vim_plsql_syntax
+" Last Change: Feb 19, 2025
+" History:  Enno Konfekt move handling of optional syntax folding from syntax
+"               file to ftplugin
+
+if exists("b:did_ftplugin") | finish | endif
+let b:did_ftplugin = 1
+
+if get(g:,"plsql_fold",0) == 1
+    setlocal foldmethod=syntax
+    let b:undo_ftplugin = "setl fdm< "
+endif