feat: specify KO_DOCKER_REPO in .ko.yaml

[miguelvr]

Description

In order to facilitate local reproducible builds for developers, it would be a nicer UX if we could specify a default image repo, globally or per image, in .ko.yaml. This can be useful in scenarios like monorepos and generally reduces the surface for user error.

Proposal

For images with different repos:

imageRepo: ghcr.io/org/repo1

- id: foo
  dir: ./foo
  main: . 
- id: bar
  dir: ./bar
  main: . 
  imageRepo: ghcr.io/org/repo2

foo → pushed to ghcr.io/org/repo/foo
bar → pushed to ghcr.io/org/repo2/bar

Note

To keep backward compatibility, KO_DOCKER_REPO would overwrite any of these options.

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[n0nvme]

Will be extremely useful for building with --bare flag