Allow specify bearer token on Registry

[jonesbusy]

In some scenario the Bearer Auth token is requested by an other system (for example token exchange).

Right now passing a known auth token is not user friendly. Typically

BearerTokenProvider provider = new BearerTokenProvider();
provider.setToken(new HttpClient.TokenResponse("...", null, null, null, null));
Registry registry = Registry.builder()
        .defaults("registry")
        .withAuthProvider(provider)
        .build();

Either improve signature of BearerTokenProvider or implement withBearerToken

Caller would be responsible to refresh token when expired (this would invalidate the Registry and require a copy with new access token)

My use case is an Artifactory MCP were tokens are exchanged using /access/api/v1/oidc/token endpoint then used as authentication