Add ensure-genmanifest role

Change-Id: Ifebf9da8cd8eeaa9cec621e490064a0f935ddbe0
diff --git a/roles/ensure-genmanifest/defaults/main.yaml b/roles/ensure-genmanifest/defaults/main.yaml
new file mode 100644
index 0000000..a17151d
--- /dev/null
+++ b/roles/ensure-genmanifest/defaults/main.yaml
@@ -0,0 +1,2 @@
+---
+genmanifest_version: latest
diff --git a/roles/ensure-genmanifest/tasks/main.yaml b/roles/ensure-genmanifest/tasks/main.yaml
new file mode 100644
index 0000000..2732814
--- /dev/null
+++ b/roles/ensure-genmanifest/tasks/main.yaml
@@ -0,0 +1,10 @@
+- name: Ensure Go is installed
+  include_role:
+    name: ensure-go
+  vars:
+    go_version: 1.16
+- name: Install genmanifest
+  include_role:
+    name: go
+  vars:
+    go_command: "install gomodules.avm99963.com/webext/genmanifest@{{ genmanifest_version }}"