Feature - Support creation/deletion of Service Tokens

[b-per]

Feature request to support the creation/deletion of service tokens.

CRUD endpoints:

• Create (2 steps)
  • Create Service Token
  • and Assign Service Token Permissions
  • the format is the same as for group permissions, so we should be able to leverage some code
• Read
  • Retrieve Service Token with its permissions
• Update
  • We should not allow updating a Service Token. Once created it can only be Read or Deleted
• Delete
  • Not documented, but a simple DELETE works fine

[b-per]

Just letting people know that I have been working on it and will be pushing a PR in the next days