Bugfix/logout on access denied page

[DeepDiver1975]

Description

1. there is a logout link now in the access denied page including some descriptive text about it
2. themable helpdesk message now translated

How to test

• add following to themes/owncloud.json file

{
  "general": {
    "name": "ownCloud",
    "slogan": "ownCloud – A safe home for all your data",
    "helpDeskText": {
      "en": "You are not one of the 300 Spartans, if you think this message shows up in error please contact King Leonidas",
      "de": "Sie keiner der 300 Spartiaten. Wenn Sie der Meinung sind, dass diese Meldung irrtümlich angezeigt wird, wenden Sie sich bitte an König Leonidas"
    },
  },
  "logo": {
    "favicon": "themes/owncloud/favicon.jpg"
  }
}

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:

Open tasks:

• ...

[ownclouders]

💥 Acceptance tests webUIPrivateLinks failed. Please find the screenshots inside ...

https://drone.owncloud.com/owncloud/phoenix/5558/

[ownclouders]

💥 Acceptance tests XGAPortrait failed. Please find the screenshots inside ...

https://drone.owncloud.com/owncloud/phoenix/5562/

[DeepDiver1975]

fixes #2102