Add bucket logging (#134)

* Add logging

* Improve syntax

* Add example

* Improve type for retention policy

modules/gcs/variables.tf

@@ -86,6 +86,18 @@ variable "versioning" {
 
 variable "retention_policies" {
   description = "Per-bucket retention policy."
-  type        = map(map(string))
+  type = map(object({
+  		retention_period = number
+		is_locked        = bool
+	}))
+  default     = {}
+}
+
+variable "logging_config" {
+  description = "Per-bucket logging."
+  type = map(object({
+  		log_bucket = string
+  		log_object_prefix = string
+	}))
   default     = {}
 }