patch 9.1.0453: filetype: rasi files are not recognized

Problem:  filetype: rasi files are not recognized
Solution: regonize '*.rasi' files as rasi filetype,
          include a filetype and syntax plugin
          (Pierrick Guillaume)

ported from: https://github.com/Fymyte/rasi.vim

closes: #14821

Signed-off-by: Pierrick Guillaume <pierguill@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/ftplugin/rasi.vim

@@ -0,0 +1,25 @@
+" Vim filetype plugin file
+" Language:		RASI
+" Maintainer:		Pierrick Guillaume <pierguill@gmail.com>
+" Last Change:		2024 May 21
+
+if exists("b:did_ftplugin")
+  finish
+endif
+let b:did_ftplugin = 1
+
+let s:cpo_save = &cpo
+set cpo&vim
+
+let b:undo_ftplugin = "setl com< cms< isk< inc<"
+
+setlocal comments=s1:/*,mb:*,ex:*/
+setlocal commentstring=//\ %s
+setlocal iskeyword+=-
+
+let &l:include = '^\s*@import\s\+\%(url(\)\='
+
+let &cpo = s:cpo_save
+unlet s:cpo_save
+
+" vim: ts=8