lint: Further recognize more JavaScript file extensions.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

.editorconfig

@@ -12,7 +12,7 @@ trim_trailing_whitespace = true
 binary_next_line = true
 switch_case_indent = true
 
-[{*.{js,json,ts},check-openapi}]
+[{*.{cjs,cts,js,json,mjs,mts,ts},check-openapi}]
 max_line_length = 100
 
 [*.{py,pyi}]

.eslintrc.js

@@ -155,7 +155,7 @@ module.exports = {
             },
         },
         {
-            files: ["**/*.ts"],
+            files: ["**/*.cts", "**/*.mts", "**/*.ts"],
             excludedFiles: "help-beta/**",
             extends: [
                 "plugin:@typescript-eslint/strict-type-checked",