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: #17751

Signed-off-by: Riley Bruins <ribru17@hotmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

.github/MAINTAINERS

@@ -252,6 +252,7 @@ runtime/ftplugin/pbtxt.vim				@lakshayg
 runtime/ftplugin/pdf.vim				@tpope
 runtime/ftplugin/perl.vim				@petdance @dkearns
 runtime/ftplugin/php.vim				@dkearns
+runtime/ftplugin/pkl.vim				@ribru17
 runtime/ftplugin/plsql.vim				@lee-lindley
 runtime/ftplugin/pod.vim				@petdance @dkearns
 runtime/ftplugin/poefilter.vim				@ObserverOfTime

runtime/filetype.vim

@@ -1957,6 +1957,9 @@ au BufNewFile,BufRead Pipfile.lock		setf json
 " Pixi lock
 au BufNewFile,BufRead pixi.lock			setf yaml
 
+" Pkl
+au BufNewFile,BufRead *.pkl			setf pkl
+
 " PL/1, PL/I
 au BufNewFile,BufRead *.pli,*.pl1		setf pli
 

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<'

src/testdir/test_filetype.vim

@@ -605,6 +605,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     pilrc: ['file.rcp'],
     pine: ['.pinerc', 'pinerc', '.pinercex', 'pinercex'],
     pinfo: ['/etc/pinforc', '/.pinforc', 'any/.pinforc', 'any/etc/pinforc'],
+    pkl: ['file.pkl'],
     pli: ['file.pli', 'file.pl1'],
     plm: ['file.plm', 'file.p36', 'file.pac'],
     plp: ['file.plp'],

src/version.c

@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1549,
 /**/
     1548,
 /**/