Add asymmetric JWT signing (#16010)

* Added asymmetric token signing.

* Load signing key from settings.

* Added optional kid parameter.

* Updated documentation.

* Add "kid" to token header.

cmd/generate.go

@@ -71,7 +71,7 @@ func runGenerateInternalToken(c *cli.Context) error {
 }
 
 func runGenerateLfsJwtSecret(c *cli.Context) error {
-	JWTSecretBase64, err := generate.NewJwtSecret()
+	JWTSecretBase64, err := generate.NewJwtSecretBase64()
 	if err != nil {
 		return err
 	}