Policy package support for Rucio server

[rdimaio]

Initial PR to add policy package support to the Rucio server.

Current questions:

• Does the |'d command work when using multiple packages? (edit: it does)

[rdimaio]

Amended version works correctly. Used these values:

policyPackages:
  enabled: true
  # Make sure the trailing slash is present
  mountPath: /opt/policy_packages/
  # Use underscores instead of hyphens for package names
  # (e.g. atlas_rucio_policy_package instead of atlas-rucio-policy-package)
  packages:
    - moduleName: atlas_rucio_policy_package
      requirement: atlas-rucio-policy-package==0.4.0
      version: 0.4.0
    - moduleName: belleii_rucio_policy_package
      requirement: git+https://github.com/rucio/temporary-belle2-policy-package@v0.1.0
      version: 0.1.0
  resources:
    requests:
      storage: 100Mi

First deployment installs both policy packages as expected, second deployment does not install anything as they already installed.

[dchristidis]

Looks fine. I took the liberty of making a few additional style-related comments that are undoubtedly a matter of personal opinion. They apply in general and not exclusively to the lines and/or file they refer to. Feel free to ignore them.