vim-patch:9.1.1549: filetype: pkl files are not recognized

Problem:  filetype: pkl files are not recognized
Solution: detect *.pkl files as pkl filetype, include
          a filetype plugin (Riley Bruins)

References:
https://pkl-lang.org/
https://github.com/apple/pkl

closes: vim/vim#17751

d128889b30

Co-authored-by: Riley Bruins <ribru17@hotmail.com>

runtime/ftplugin/pkl.vim

@@ -0,0 +1,14 @@
+" Vim filetype plugin
+" Language:	Pkl
+" Maintainer:	Riley Bruins <ribru17@gmail.com>
+" Last Change:	2025 Jul 14
+
+if exists('b:did_ftplugin')
+  finish
+endif
+let b:did_ftplugin = 1
+
+setlocal comments=sO:*\ -,mO:*\ \ ,exO:*/,s1:/*,mb:*,ex:*/,://
+setlocal commentstring=//\ %s
+
+let b:undo_ftplugin = 'setl com< cms<'

runtime/lua/vim/filetype.lua

@@ -949,6 +949,7 @@ local extension = {
   pike = 'pike',
   pmod = 'pike',
   rcp = 'pilrc',
+  pkl = 'pkl',
   PL = detect.pl,
   pli = 'pli',
   pl1 = 'pli',