Add web-ext-lint job

Change-Id: I12018ea457599ba0dd611c05464f3c1dd14d0fba
diff --git a/roles/ensure-web-ext/tasks/main.yaml b/roles/ensure-web-ext/tasks/main.yaml
new file mode 100644
index 0000000..6a9f0e3
--- /dev/null
+++ b/roles/ensure-web-ext/tasks/main.yaml
@@ -0,0 +1,7 @@
+- name: Ensure NodeJS is installed
+  include_role:
+    name: ensure-nodejs
+  vars:
+    node_version: 14
+- name: Install web-ext
+  command: "npm install --global web-ext"