Oauth multi resource support

[MarcialRosales]

Proposed Changes

see #7746

Types of Changes

What types of changes does your code introduce to this project?
Put an x in the boxes that apply

• Bug fix (non-breaking change which fixes issue #NNNN)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause an observable behavior change in existing systems)
• Documentation improvements (corrections, new content, etc)
• Cosmetic change (whitespace, formatting, etc)
• Build system and/or CI

Tasks

• Use keycloak for selenium tests because it is easier to configure TLS for jwks
• Clear oidc client library's state either just before redirecting the user to the authorization server or when an error occurs
• Take into account initiated_login_type . Atm it assumes it is sp_initiated from the selection box
• Include basic authentication to the initial page if enabled
• Rename all selenium's .env files to env to facilitate merging in some editing tools
• Refactored all components' start_ and init_ functions out from suite_template
• Write documentation : Allow Oauth2 and basic auth for management UI and support multiple oauth2 resources rabbitmq-website#1710
• Replace rabbitmqctl command add_uaa_key with add_signing_key. Keep àdd_uaa_key` around for at least a release or two. Announce in release notes that it will be soon deprecated. The command's description also says that it is deprecated although it is fully functional.

[MarcialRosales]

Deprecated by this other PR which fully implemented the multi-oauth feature.