WIP: extract sig data into file

[dhiller]

What this PR does / why we need it:

Extracts the sig data for sig-ci into a separate file. Also adds approvers and reviewers into the file - aiming towards making that file the single source of truth.

This could serve as a building block for OWNERS_ALIASES sync and also automated generation of GitHub teams.

Furthermore this makes the groups (SIGs, WGs, UGs, Committees) more autonomous, since SIG chairs can approve the changes themselves, once they have extracted the group.yaml into their group directory.

Note

Leaves the original file sigs.yaml for backwards compatibility, however the goal is to entirely remove that one and only use sigs.ReadFile()

Note

Currently we require to run make generate in order to have updates rendered into the sig-list.md, however that should be done as a postsubmit job instead.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Related to kubevirt/project-infra#5317

[kubevirt-prow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[kubevirt-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign vladikr for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[dhiller]

FYI @aburdenthehand @iholder101 @xpivarc

[kubevirt-prow]

PR needs rebase.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.