feat: support custom roles

[ecmadao]

resource "bytebase_role" "auditor" {
  resource_id = "auditor-role"
  title       = "Auditor role"
  description = "This role can only list audit logs"
  permissions = [
    "bb.auditLogs.search"
  ]
}

resource "bytebase_user" "workspace_auditor" {
  depends_on = [
    bytebase_role.auditor
  ]
  title = "Auditor"
  email = "[email protected]"

  # Grant workspace level roles.
  roles = [bytebase_role.auditor.name]
}