Make default Fuseki access settings more secure

### Version

4.7.0

### Feature

As configured in its default [shiro.ini](https://github.com/apache/jena/blob/main/jena-fuseki2/jena-fuseki-webapp/src/main/resources/org/apache/jena/fuseki/webapp/shiro.ini), a Fuseki server allows read- and write-access from anywhere by default. This is a very dangerous default. I'd change this to

1. Limit admin protocol endpoint `/$/metrics` to localhost
2. Enable simple username/password authentication for write access (SPARQL Update and Graph Store Protocol except GET/HEAD) unless from localhost

Sure this is insecure still but at least just changing the default password will restrict public write access to all your data.

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

Yes

Start with jena-fuseki2/jena-fuseki-webapp/src/main/resources/org/apache/jena/fuseki/webapp/shiro.ini, the default access configuration named in the issue. Review the existing rules for /$/metrics and remote write access, then verify that the requested localhost restriction and authentication behavior are represented in the default settings.

Written by the indexing model from the issue text.