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

tokenserver/api/token_file.pb.go

Index: tokenserver/api/token_file.pb.go
diff --git a/tokenserver/api/token_file.pb.go b/tokenserver/api/token_file.pb.go
index f9b6994b0bba7116437b9ed8dd8869773ad122d1..5cefa9be50c62a31ac25840c8b1c04614aa10053 100644
--- a/tokenserver/api/token_file.pb.go
+++ b/tokenserver/api/token_file.pb.go
@@ -48,7 +48,7 @@ type TokenFile struct {
 func (m *TokenFile) Reset()                    { *m = TokenFile{} }
 func (m *TokenFile) String() string            { return proto.CompactTextString(m) }
 func (*TokenFile) ProtoMessage()               {}
-func (*TokenFile) Descriptor() ([]byte, []int) { return fileDescriptor1, []int{0} }
+func (*TokenFile) Descriptor() ([]byte, []int) { return fileDescriptor2, []int{0} }
 
 func (m *TokenFile) GetAccessToken() string {
 	if m != nil {
@@ -118,10 +118,10 @@ func init() {
 }
 
 func init() {
-	proto.RegisterFile("github.com/luci/luci-go/tokenserver/api/token_file.proto", fileDescriptor1)
+	proto.RegisterFile("github.com/luci/luci-go/tokenserver/api/token_file.proto", fileDescriptor2)
 }
 
-var fileDescriptor1 = []byte{
+var fileDescriptor2 = []byte{
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 	0x14, 0x85, 0x95, 0xf6, 0xff, 0x03, 0xbd, 0xed, 0x64, 0x09, 0x64, 0x16, 0x14, 0x75, 0xca, 0x42,