Make JwtBearerService public and its methods virtual for extensibility

[marcominerva]

Feature Request

Please make the JwtBearerService class public. This would allow developers to create multiple wrappers with different configurations, enabling greater flexibility (for example, instantiating it as a KeyService).

Additionally, make all public methods of JwtBearerService virtual so they can be overridden. This will improve extensibility and allow advanced users to customize the authentication logic as needed.

Rationale:

• Public visibility allows users to instantiate JwtBearerService as needed in various scenarios.
• Virtual methods facilitate extension and customization without changes to the core package.

Example Use Cases:

• Creating different services for distinct JWT configurations
• Overriding default behavior for custom key validation

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If this change is acceptable, please outline any potential impacts on the public API and document the new usage pattern.