Check username for allowed characters when new user is created

[subotic]

Creating a user with "username": "[email protected]" should not be possible.

[loicjaouen]

it is also possible to create a user donald-duck that is then referred as invalid:

POST http://localhost:3333/admin/users

{
  "email": "[email protected]",
  "givenName": "Donald",
  "familyName": "Duck",
  "username": "donald-duck",
  "password": "test",
  "status": true,
  "lang": "en",
  "systemAdmin": false
}

returns:

{
    "user": {
        "email": "[email protected]",
        "familyName": "Duck",
        "givenName": "Donald",
        "groups": [],
        "id": "http://rdfh.ch/users/mCjxMQ4xQuq12LjaS7qXTQ",
        "lang": "en",
        "password": null,
        "permissions": {
            "administrativePermissionsPerProject": {},
            "groupsPerProject": {}
        },
        "projects": [],
        "sessionId": null,
        "status": true,
        "token": null,
        "username": "donald-duck"
    }
}

but then the query:

GET http://localhost:3333/admin/users/username/donald-duck

returns:

{
    "error": "org.knora.webapi.BadRequestException: Invalid username Some(donald-duck)"
}

[gfoo]

@loicjaouen see rules given in original issue by @subotic #1573 (comment)

[subotic]

@loicjaouen Thanks for reporting. Did you try it against the linked PR branch?

[subotic]

I've added a test for -, which the patched version handles correctly.

I've also added validation checks for when an existing username or email wants to be changed into something not allowed.