Replaces (updates) a taxonomy and all its policy tags. The taxonomy and its entire hierarchy of policy tags must be represented literally by SerializedTaxonomy and the nested SerializedPolicyTag messages. This operation automatically does the following: - Deletes the existing policy tags that are missing from the SerializedPolicyTag. - Creates policy tags that don't have resource names. They are considered new. - Updates policy tags with valid resources names accordingly.