Add type import check to eslint

.eslintrc.json

@@ -124,7 +124,9 @@
     "lit-a11y/no-autofocus": "off",
     "lit-a11y/alt-text": "warn",
     "lit-a11y/anchor-is-valid": "warn",
-    "lit-a11y/role-has-required-aria-attrs": "warn"
+    "lit-a11y/role-has-required-aria-attrs": "warn",
+    "@typescript-eslint/consistent-type-imports": "error",
+    "@typescript-eslint/no-import-type-side-effects": "error"
   },
   "plugins": ["unused-imports"]
 }