[Authentication] Ability to configure fuseki authentication through the config file

### Version

latest

### Feature

Dear,
Currently Apache Jena throug its API support the [bearer authentication](https://jena.apache.org/documentation/sparql-apis/http-auth.html#bearer-authentication), but for non java developer user is often a no go.
It is possible to add some buisness logic into fuseki to do the job (maybe in other executable too) in order to configure it through the config file

As example below a tool which allow such feature for inspiration:
- https://github.com/matrix-org/synapse/blob/4eb2f4e02b83c90519a8a55c562d1fafab7caf0b/docs/openid.md
Personally I am interested for the Keycloak support

such config file would allow enoug flexibility for end user and enough information for Jena services to works as expected without the need to develop a Java application.

Thanks

### Are you interested in contributing a solution yourself?

None

Start by reading the Apache Jena bearer-authentication documentation linked in the issue and the Fuseki configuration documentation. Define the supported authentication configuration, including the requested Keycloak case, and verify that Fuseki services can use it without a separate Java application.

Written by the indexing model from the issue text.