Missing Authorization policy Role list

Currently changing authorization roles for an app requires modifying the policy.xml file that is copied into the project when creating a new app. The default file gives access to "DAGL" and "REGNA" (director general and accounting respectively). There is a long list of roles that a user can have, available in Norwegian [here](https://www.altinn.no/hjelp/skjema/alle-altinn-roller/), but it does not contain the codes needed to edit the policy.xml file.

The only place I have found that has these codes documented is inside the development environment for Altinn 2 (TUL), which can be a real hassle to log in to.

An overview should be published here in altinn-studio-docs, and be linked to from the [documentation of the policy.xml-file](https://docs.altinn.studio/technology/architecture/components/application/solution/altinn-studio/designer/pap/xacmlpolicy/).

Start with the linked policy.xml documentation and the existing Altinn Studio documentation structure, then compare the Norwegian role list with the role codes available in TUL. Publish an overview of the role codes in altinn-studio-docs and link it from the policy.xml documentation; verify that users can find both the roles and their codes without accessing TUL.

Written by the indexing model from the issue text.