refact(authmethods): Add top level token type to Authenticate (#2010)

Other parts of the system make use of a "type" field, while the
AuthenticateResponse sets a "token_type" on the response attributes
directly. Rename this field to "type", and move it up to the response
level, to be more consistent with other RPCs.

Also adds a new field to the AuthenticateRequest, "type" which will
replace the "token_type" field over time.

internal/proto/controller/api/services/v1/auth_method_service.proto

@@ -202,8 +202,11 @@ message AuthenticateRequest {
   // The ID of the Auth Method in the system that should be used for authentication.
   string auth_method_id = 1 [json_name = "auth_method_id"];  // @gotags: `class:"public"`
   // This can be "cookie" or "token". If not provided, "token" will be used. "cookie" activates a split-cookie method where the token is split partially between http-only and regular cookies in order
+  // to keep it safe from rogue JS in the browser. Deprecated, use "type" instead.
+  string token_type = 2 [json_name = "token_type", deprecated = true];  // @gotags: `class:"public"`
+  // This can be "cookie" or "token". If not provided, "token" will be used. "cookie" activates a split-cookie method where the token is split partially between http-only and regular cookies in order
   // to keep it safe from rogue JS in the browser.
-  string token_type = 2 [json_name = "token_type"];  // @gotags: `class:"public"`
+  string type = 6 [json_name = "type"];  // @gotags: `class:"public"`
   // Attributes are passed to the Auth Method; the valid keys and values depend on the type of Auth Method as well as the command.
   google.protobuf.Struct attributes = 4 [json_name = "attributes"];
   // The command to perform.
@@ -217,6 +220,8 @@ message AuthenticateRequest {
 message AuthenticateResponse {
   reserved 1, 2;  // Old item and token_type
   reserved "item", "token_type";
+  // The type of the token returned. Either "cookie" or "token".
+  string type = 3;  // @gotags: `class:"public"`
   // Valid keys and values depend on the type of Auth Method as well as the command.
   google.protobuf.Struct attributes = 4 [json_name = "attributes"];
   // The command that was performed.