[FEATURE] Add users to client when created

[LufinityLucas]

Is your feature request related to a problem? Please describe.
When new users are created during, in my case, the OIDC login process (by setting $oidcCreateUser to true), they are not member of any client and as such do not have access to any projects. A nice feature would be to have them added to a specified default client.

Describe the solution you'd like
This should probably have been a pull request, but I'm to unsure how to do one properly. 😄

In /app/Domain/Oidc/Services/Oidc.php, add e.g.,

...
private int $defaultClient = 0;
...
$this->defaultClient = $this->config->get('oidcDefaultClient', 0);
...

And in the same file when running the createUser method, change 'clientId' => '' to 'clientId' => $this->defaultClient,

At last, add it to wherever default configurations are stored, e.g., in /app/Core/DefaultConfig.php, add public int $oidcDefaultClient = 0;.

[marcelfolaron]

I like that. We should do that. Will keep this in mind for our next iteration