open api for get session ak/sk/token from signer

Signed-off-by: gaort <rutong.grt@alibaba-inc.com>

sdk/auth/signers/signer_ecs_ram_role.go

@@ -166,7 +166,7 @@ func (signer *EcsRamRoleSigner) refreshCredential(response *responses.CommonResp
 	return
 }
 
-func (signer *EcsRamRoleSigner) GetSessionCredential()(*SessionCredential){
+func (signer *EcsRamRoleSigner) GetSessionCredential() *SessionCredential {
 	return signer.sessionCredential
 }
 

sdk/auth/signers/signer_ram_role_arn.go

@@ -165,7 +165,7 @@ func (signer *RamRoleArnSigner) refreshCredential(response *responses.CommonResp
 	return
 }
 
-func (signer *RamRoleArnSigner) GetSessionCredential()(*SessionCredential){
+func (signer *RamRoleArnSigner) GetSessionCredential() *SessionCredential {
 	return signer.sessionCredential
 }