Adding Zen Browser matugen template (#1181)

* Adding Zen Browser matugen template

* Fixing indentation for matugen.go edits

* Trying to fix linting again..

* Tweaking contrasting surface colors in css, renamed file to match how firefox userchrome is named, also changed output directory to DMS config directory (like firefox)

* Modifing Zen userChrome again: removing unused css stuff, tweaking colors to better align with how pywalfox handles backgrounds/toolbars

* Last few tweaks on CSS - changing url bar highlight color, changing contrast on selected urls in dropdown

* matugen.go: fix check command for zen browser

* search_index: add zen browser setting

core/internal/matugen/matugen.go

@@ -255,6 +255,9 @@ output_path = '%s'
 	if !opts.ShouldSkipTemplate("pywalfox") {
 		appendConfig(opts, cfgFile, "pywalfox", "pywalfox.toml")
 	}
+	if !opts.ShouldSkipTemplate("zenbrowser") {
+		appendConfig(opts, cfgFile, "zen", "zenbrowser.toml")
+	}
 	if !opts.ShouldSkipTemplate("vesktop") {
 		appendConfig(opts, cfgFile, "vesktop", "vesktop.toml")
 	}