token-server: Add protos for new API for generating service account tokens.

tokenserver/client/tokenclient_test.go

Index: tokenserver/client/tokenclient_test.go
diff --git a/tokenserver/client/tokenclient_test.go b/tokenserver/client/tokenclient_test.go
index 8427d18dc94c0b442fcb82b6cb54c88f3ba16f7b..d620230561cbdcd3dd56be4d63bd4bc3e78334ec 100644
--- a/tokenserver/client/tokenclient_test.go
+++ b/tokenserver/client/tokenclient_test.go
@@ -97,6 +97,14 @@ func (f *fakeRPCClient) MintDelegationToken(context.Context, *minter.MintDelegat
 	panic("not implemented")
 }
 
+func (f *fakeRPCClient) MintOAuthTokenGrant(context.Context, *minter.MintOAuthTokenGrantRequest, ...grpc.CallOption) (*minter.MintOAuthTokenGrantResponse, error) {
+	panic("not implemented")
+}
+
+func (f *fakeRPCClient) MintOAuthTokenViaGrant(context.Context, *minter.MintOAuthTokenViaGrantRequest, ...grpc.CallOption) (*minter.MintOAuthTokenViaGrantResponse, error) {
+	panic("not implemented")
+}
+
 // fakeSigner implements Signer.
 type fakeSigner struct{}