Add ArgoCD as an optional module

oci-managed/argocd/provider.tf

@@ -0,0 +1,12 @@
+terraform {
+  required_providers {
+    helm = {
+      source  = "hashicorp/helm"
+      version = ">= 2.12.1"
+    }
+    kubectl = {
+      source  = "gavinbunney/kubectl"
+      version = ">= 1.14.0"
+    }
+  }
+}