Merge #3083

3083: Provide a local-config in the Nix configuration r=EncodePanda a=EncodePanda

Closes: IntersectMBO/ouroboros-network#3078 and IntersectMBO/ouroboros-network#2982

`local-config.nix` holds a centralized configuration for the project. For now, this is just a GHC version that we use. Follow-up PRs may extend this.

Note that this configuration is provided as an overlay in `nix/default.nix`.

Co-authored-by: EncodePanda <[email protected]>
Co-authored-by: Javier Sagredo <[email protected]>

Author: 3 people