patch 9.1.1878: filetype: Soy files are not recognized

Problem:  filetype: Soy files are not recognized
Solution: Detect *.soy files as soy filetype,
          include a soy filetype plugin (Riley Bruins)

closes: #18640

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

.github/MAINTAINERS

@@ -289,6 +289,7 @@ runtime/ftplugin/slint.vim				@ribru17
 runtime/ftplugin/snakemake.vim				@ribru17
 runtime/ftplugin/solidity.vim				@coti-z
 runtime/ftplugin/solution.vim				@dkearns
+runtime/ftplugin/soy.vim				@ribru17
 runtime/ftplugin/spajson.vim				@dseomn
 runtime/ftplugin/spec.vim				@ignatenkobrain
 runtime/ftplugin/squirrel.vim				@ribru17

runtime/autoload/dist/ft.vim

@@ -2714,6 +2714,8 @@ const ft_from_ext = {
   "hlp": "smcl",
   "ihlp": "smcl",
   "smcl": "smcl",
+  # Soy
+  "soy": "soy",
   # Stored Procedures
   "stp": "stp",
   # Standard ML

runtime/ftplugin/soy.vim

@@ -0,0 +1,14 @@
+" Vim filetype plugin
+" Language:	Soy (Closure Templates)
+" Maintainer:	Riley Bruins <ribru17@gmail.com>
+" Last Change:	2025 Oct 24
+
+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 = "setlocal comments< commentstring<"

src/testdir/test_filetype.vim

@@ -747,6 +747,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     snobol4: ['file.sno', 'file.spt'],
     solidity: ['file.sol'],
     solution: ['file.sln'],
+    soy: ['file.soy'],
     spajson: ['any/pipewire/file.conf', 'any/pipewire/file.conf.d/other.conf',
               'any/wireplumber/file.conf', 'any/wireplumber/file.conf.d/other.conf'],
     sparql: ['file.rq', 'file.sparql'],

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1878,
 /**/
     1877,
 /**/