This way we can avoid rebuilding Nim every time we build packages.
Compilation of `libwaku` with Nim: 9 minutes
Compilation of `libwaku` without Nim: 5 minutes
Notably this upgrades:
- Nim from 2.2.4 to 2.2.8.
- Zerokit from 0.9.0 to 1.0.0.
Also added CODEOWNERS file for CI and Nix configuration.
Depends on:
https://github.com/status-im/nimbus-build-system/pull/112
Signed-off-by: Jakub Sokołowski <jakub@status.im>