Remove auth related legacy code

[t83714]

Remove auth related legacy code

Including:

• Any code (both frontend & backend) related to authnReadPolicyId
• Used Policy files: magda-opa/policies/object/registry
• remove obsolete middleware & directives
• remove unused OPA parser
• remove obsolete resource / operations

[t83714]

done all items except remove obsolete middleware & directives in PR: #3347.
Create the following tickets for remove obsolete middleware & directives:

• Secure admin API with new auth model #3350
• Secure tenant API with new auth model #3351
• Secure content API with new auth model #3349
• Secure openfaas gateway with new auth model #3348
• Remove usage of MUST_BE_ADMIN middleware in auth API #3352

[t83714]

Re: above tickets:
When tackling those tickets, we probably want to:

• Propose the design re: how API access map to the current auth “resource” / “operation” model
  • E.g. you can either create a new resource “api/xxxAPI” & operations e.g. “api/xxxApi/xxxoperation”
  • OR bind the access to defined “resource” e.g. an API to read dataset can request permission to defined “object/dataset/read”
• Leverage existing auth middleware to replace existing “admin-only” middleware
  • withAuthDecision middleware is the base middleware can be used to ask generic auth decision from the policy engine
    • There are a few more specialised middlewares built on top of it (available in the same file) that you might also want to have a look
  • For anyone's interest, the scala version “withAuthDecision Akka Directive” is here

[t83714]

closed via PR: #3390