Refactor Auth Service Protos, Add Access Rules (#1411)

* Refactor auth/service into two protos

* Accounts Proto

* Store Prefixes

* Misc

* Tweak Protos

Co-authored-by: Ben Toogood <ben@micro.mu>
Co-authored-by: Asim Aslam <asim@aslam.me>

auth/service/proto/accounts/accounts.proto

@@ -0,0 +1,16 @@
+syntax = "proto3";
+
+package go.micro.auth;
+
+import "github.com/micro/go-micro/auth/service/proto/auth/auth.proto";
+
+service Accounts {
+  rpc List(ListAccountsRequest) returns (ListAccountsResponse) {};
+}
+
+message ListAccountsRequest {
+}
+
+message ListAccountsResponse {
+  repeated Account accounts = 1;
+}