patch 9.0.2098: No filetype support for xcompose files

Problem:  No filetype support for xcompose files
Solution: Add filetype detection

closes: #13508

Signed-off-by: ObserverOfTime <chronobserver@disroot.org>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index cd64800..d99c8c7 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -237,6 +237,7 @@
 runtime/ftplugin/wast.vim		@rhysd
 runtime/ftplugin/wget.vim		@dkearns
 runtime/ftplugin/wget2.vim		@dkearns
+runtime/ftplugin/xcompose.vim		@ObserverOfTime
 runtime/ftplugin/xml.vim		@chrisbra
 runtime/ftplugin/xs.vim			@petdance
 runtime/ftplugin/zsh.vim		@chrisbra
@@ -525,6 +526,7 @@
 runtime/syntax/wget.vim			@dkearns
 runtime/syntax/wget2.vim		@dkearns
 runtime/syntax/xbl.vim			@dkearns
+runtime/syntax/xcompose.vim		@ObserverOfTime
 runtime/syntax/xmath.vim		@cecamp
 runtime/syntax/xml.vim			@chrisbra
 runtime/syntax/xs.vim			@petdance