Finish the integration test: login and user create wallet

[dadiorchen]

For a logged in user (got access key already), they should be able to create wallet under their account, by calling POST /wallets
Please write test to cover this workflow, it is okay to use postman or other to do the login and get the access token then do the post /wallets, but in the integration test, it is unnecessary to do it for real, just mock these outward request and focus on the internal business.

[GabriellaAmah]

Hi @dadiorchen can you please assign this to me, recently joined the team and i think this would be a way to contribute and get involved.