Oauth2: Support variable expansion when checking resource access

[MarcialRosales]

Proposed Changes

This PR adds variable expansion when checking resource access or vhost access on oauth2 authentication backend. RabbitMQ only supported variable expansion when checking topic access.

It addresses feature request #13894

Types of Changes

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• 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