Add Support for JWK Cache Configuration in Resource Server

[amaraslam07]

Is your feature request related to a problem? Please describe.
When building the resource server configuration, there is no option to provide the JWK cache which can be passed to the NimbusJwtDecoder when building the object. This results in the JWK being refreshed every 5 minutes.

Describe the solution you'd like
I would like to have an option to provide the JWK cache in the resource server configuration. This would allow the NimbusJwtDecoder to use the cache and avoid frequent JWK refreshes.

Describe alternatives you've considered
The workaround is to build out the JwtDecoder bean manually, but this requires copying the createDefaultValidator private method from the library. Here is an example:

@Bean
@Primary
JwtDecoder jwtDecoder(AadAuthenticationProperties aadAuthenticationProperties, CacheManager cacheManager) {
    AadAuthorizationServerEndpoints identityEndpoints = new AadAuthorizationServerEndpoints(
            aadAuthenticationProperties.getProfile().getEnvironment().getActiveDirectoryEndpoint(), aadAuthenticationProperties.getProfile().getTenantId());

    Cache cache = cacheManager.getCache("jwtCache");
    NimbusJwtDecoder nimbusJwtDecoder = NimbusJwtDecoder
            .withJwkSetUri(identityEndpoints.getJwkSetEndpoint())
            .restOperations(createRestTemplate(restTemplateBuilder))
            .cache(cache)
            .build();
    List<OAuth2TokenValidator<Jwt>> validators = createDefaultValidator(aadAuthenticationProperties);
    nimbusJwtDecoder.setJwtValidator(new DelegatingOAuth2TokenValidator<>(validators));
    return nimbusJwtDecoder;
}

https://github.com/Azure/azure-sdk-for-java/blob/main/sdk/spring/spring-cloud-azure-autoconfigure/src/main/java/com/azure/spring/cloud/autoconfigure/implementation/aad/configuration/AadResourceServerConfiguration.java

Additional context
The following properties are not working in the context of the resource server:

• spring.cloud.azure.active-directory.jwk-set-cache-lifespan
• spring.cloud.azure.active-directory.jwk-set-cache-refresh-time

Currently, this results in the JWK being refreshed every 5 minutes. This can add up to significant delays in a microservices environment where multiple services fetch keys simultaneously, resulting in 200 to 300ms delays including parsing the keys on each service.

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[github-actions]

@moarychan @Netyyyy @rujche @saragluna

[github-actions]

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