feat: Implement RBAC checks on /templates endpoints (#1678)

* feat: Generic Filter method for rbac objects

coderd/rbac/object.go

@@ -6,6 +6,11 @@ import (
 
 const WildcardSymbol = "*"
 
+// Objecter returns the RBAC object for itself.
+type Objecter interface {
+	RBACObject() Object
+}
+
 // Resources are just typed objects. Making resources this way allows directly
 // passing them into an Authorize function and use the chaining api.
 var (
@@ -99,6 +104,10 @@ type Object struct {
 	// TODO: SharedUsers?
 }
 
+func (z Object) RBACObject() Object {
+	return z
+}
+
 // All returns an object matching all resources of the same type.
 func (z Object) All() Object {
 	return Object{