slightly simplify snipmate-loader.

Don't need RespectCollectionLaziness, was from earlier version.
Also don't have to load all extending filetypes in `add_file`, that
happens in `load_file`.

lua/luasnip/loaders/from_snipmate.lua

@@ -207,7 +207,7 @@ function Collection.new(root, lazy, include_ft, exclude_ft, add_opts, lazy_watch
 				o:register_file(path, file_ft)
 				if file_category == "load" then
 					-- actually load if allowed by in/exclude.
-					o:add_file(path, file_ft, "RespectCollectionLaziness")
+					o:add_file(path, file_ft)
 				end
 			end
 		end,
@@ -238,22 +238,17 @@ function Collection:register_file(path, ft)
 	self.collection_files_by_ft[ft][path] = true
 end
 
---- @alias LuaSnip.Loaders.Snipmate.LazyMode
---- | '"Immediate"' Load file immediately, independent of collection.lazy.
---- | '"RespectCollectionLaziness"' Behave according to collection.lazy.
-
 --- Register a file-filetype-association with the collection.
 --- @param path string Path to a file that belongs to this collection.
 --- @param add_ft string The original filetype this file should be added as.
 ---                      Since we have to support filetype-extensions, this may
 ---                      add the snippets of the file to several other
 ---                      filetypes.
---- @param mode LuaSnip.Loaders.Snipmate.LazyMode
-function Collection:add_file(path, add_ft, mode)
+function Collection:add_file(path, add_ft)
 	-- register known file.
 	Data.snipmate_ft_paths[add_ft][path] = true
 
-	if mode == "RespectCollectionLaziness" and self.lazy then
+	if self.lazy then
 		if not session.loaded_fts[add_ft] then
 			log.info("Registering lazy-load-snippets for ft `%s` from file `%s`", add_ft, path)
 
@@ -268,10 +263,8 @@ function Collection:add_file(path, add_ft, mode)
 		end
 	end
 
-	-- load file for add_ft and all filetypes that inherit from it.
-	for _, ft in ipairs(self.ft_extensions:connected_component(add_ft, "Forward")) do
-		self:load_file(path, ft, "SkipIfLoaded")
-	end
+	-- extended filetypes will be loaded in load_file.
+	self:load_file(path, add_ft, "SkipIfLoaded")
 end
 
 --- @alias LuaSnip.Loaders.Snipmate.SkipLoad