fix: Specify namespaces for C# and PHP

Note: this isn't marked as a breaking change in the conventional commit as it is *only* breaking for C# and PHP, and Google Cloud Client Libraries for the Access Approval API have not been released in these languages yet. Anyone who previously generated libraries for these languages will see a breaking change when they regenerate though.
PiperOrigin-RevId: 345470945

google/cloud/accessapproval/v1/accessapproval.proto

@@ -23,10 +23,12 @@ import "google/protobuf/empty.proto";
 import "google/protobuf/field_mask.proto";
 import "google/protobuf/timestamp.proto";
 
+option csharp_namespace = "Google.Cloud.AccessApproval.V1";
 option go_package = "google.golang.org/genproto/googleapis/cloud/accessapproval/v1;accessapproval";
 option java_multiple_files = true;
 option java_outer_classname = "AccessApprovalProto";
 option java_package = "com.google.cloud.accessapproval.v1";
+option php_namespace = "Google\\Cloud\\AccessApproval\\V1";
 option ruby_package = "Google::Cloud::AccessApproval::V1";
 
 // This API allows a customer to manage accesses to cloud resources by