Config cache compatibility for indra-git

Currently, indra-git has issues with the configuration cache because JGit invokes external processes to discover git configurations. We should figure how to avoid this.

https://docs.gradle.org/8.1.1/userguide/configuration_cache.html#config_cache:not_yet_implemented:build_services_in_fingerprint as well

This may require API changes -- does that involve everything returning a `Provider`?