Vault add some region configuration to specify the way the secrets are injected

To allow the onyxia helm chart to specifigy the mode and then decide to use personal vault token (today behaviour) or use the jwt service account to issue a vault token and then load the var env.

```
vault:
injection:
personalToken:
enabled: true false.
serviceAccount:
mode: jwt/kubernete
enabled: true/false
pathJwt
role
```