runtime: recognize sway file types

See https://github.com/FuelLabs/sway. Comments taken from their syntax
documentation. File extension taken from the same documentation/GitHub's
own recognition of these file types

.github/MAINTAINERS

@@ -263,6 +263,7 @@ runtime/ftplugin/squirrel.vim		@ribru17
 runtime/ftplugin/ssa.vim		@ObserverOfTime
 runtime/ftplugin/sshdconfig.vim		@jiangyinzuo
 runtime/ftplugin/svelte.vim		@igorlfs
+runtime/ftplugin/sway.vim		@ribru17
 runtime/ftplugin/swayconfig.vim		@jamespeapen
 runtime/ftplugin/systemverilog.vim	@Kocha
 runtime/ftplugin/swig.vim		@jmarrec

runtime/filetype.vim

@@ -2430,6 +2430,9 @@ au BufNewFile,BufRead *.sml			setf sml
 " Sratus VOS command macro
 au BufNewFile,BufRead *.cm			setf voscm
 
+" Sway (programming language)
+au BufNewFile,BufRead *.sw			setf sway
+
 " Swift
 au BufNewFile,BufRead *.swift,*.swiftinterface	setf swift
 au BufNewFile,BufRead *.swift.gyb		setf swiftgyb

runtime/ftplugin/sway.vim

@@ -0,0 +1,15 @@
+" Vim filetype plugin
+" Language:	Sway
+" Maintainer:	Riley Bruins <ribru17@gmail.com>
+" Last Change:	2024 Nov 01
+
+if exists('b:did_ftplugin')
+  finish
+endif
+let b:did_ftplugin = 1
+
+setl commentstring=//\ %s
+" From Rust comments
+setl comments=s0:/*!,ex:*/,s1:/*,mb:*,ex:*/,:///,://!,://
+
+let b:undo_ftplugin = 'setl com< cms<'

src/testdir/test_filetype.vim

@@ -729,6 +729,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     svelte: ['file.svelte'],
     svg: ['file.svg'],
     svn: ['svn-commitfile.tmp', 'svn-commit-file.tmp', 'svn-commit.tmp'],
+    sway: ['file.sw'],
     swayconfig: ['/home/user/.sway/config', '/home/user/.config/sway/config', '/etc/sway/config', '/etc/xdg/sway/config'],
     swift: ['file.swift', 'file.swiftinterface'],
     swiftgyb: ['file.swift.gyb'],