implementing updateuser in the admin

- [x] I have searched the [issues](https://github.com/apache/openserverless/issues) of this repository and believe that this is not a duplicate.

### Ⅰ. Issue Description
addming user twice results in secrets being lost and there is no way

### Ⅱ. Describe what happened

if you do adduser twice, the user password is updated but not resource secrets

so it results in a user with different resources but with the wrong secrets as they are being regenerates

### Ⅲ. Describe what you expected to happen
if you do adduser of an existing user, the system should warn an user exists and suggest to use updateuser instead

if you do an updateuser it should creete the user reading the current whisksusers and then update it changing the passwords but keeping the existing secrets

### Ⅳ. How to reproduce it (as minimally and precisely as possible)

### Ⅴ. Anything else we need to know?

### Ⅵ. Environment:

currert tasks