Support --all in `nix store copy-log`

[PkmX]

Is your feature request related to a problem? Please describe.

The nix store copy-log command does not support --all:

$ nix store copy-log --to <...> --all
error: unrecognised flag '--all'
Try 'nix --help' for more information.

Describe the solution you'd like

Implement the --all option to copy all build logs between stores.

Describe alternatives you've considered

Manually write a plumbing script that queries all derivations on a store and then run nix store copy-log on each of them. This should work but it would be better if it is supported by Nix itself.

Additional context

Priorities

Add 👍 to issues you find important.