runtime(kivy): update kivy syntax, include ftplugin

Kivy uses "#:" for preprocessing commands (like "#:import ...") which
were overridden by the comment syntax. This has been changed, and a
commentstring has been added.

closes: #15163

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

runtime/ftplugin/kivy.vim

@@ -0,0 +1,13 @@
+" Vim filetype plugin
+" Language:	Kivy
+" Maintainer:	Riley Bruins <ribru17@gmail.com>
+" Last Change:	2024 Jul 06
+
+if exists('b:did_ftplugin')
+  finish
+endif
+let b:did_ftplugin = 1
+
+setl commentstring=#\ %s
+
+let b:undo_ftplugin = 'setl cms<'