vim-patch:9.1.0636: filetype: ziggy files are not recognized

Problem:  filetype: ziggy files are not recognized
Solution: detect '*.ziggy' files as ziggy filetype,
          detect '*.ziggy-schema' files as ziggy-schema filetype
          (EliSauder)

References: https://ziggy-lang.io/

fixes: vim/vim#15355
closes: vim/vim#15367

f4572cee35

Co-authored-by: EliSauder <24995216+EliSauder@users.noreply.github.com>

runtime/lua/vim/filetype.lua

@@ -1246,6 +1246,8 @@ local extension = {
   z8a = 'z8a',
   zig = 'zig',
   zon = 'zig',
+  ziggy = 'ziggy',
+  ['ziggy-schema'] = 'ziggy_schema',
   zu = 'zimbu',
   zut = 'zimbutempl',
   zs = 'zserio',