feat: lint .d.ts files (#850)

Enables linting of typescript definition files to ensure correct
and consistent syntax.

BREAKING CHANGE: what was not previously linted will now be linted so it may surface new errors

Author: achingbrain

src/config/user.js

@@ -55,8 +55,7 @@ const defaults = {
       'tasks/**/*.{js,ts}',
       'benchmarks/**/*.{js,ts}',
       'utils/**/*.{js,ts}',
-      '!**/node_modules/**',
-      '!**/*.d.ts'
+      '!**/node_modules/**'
     ]
   },
   // docs cmd options