envs: can ignore zones locally as well

ignore_zones field is now a map so that its keys can be set not only for the CI.

When a zone is declared in ci.cue in ignore_zones the zone is ignored in the CI like before.

When a zone is declared in envs.cue in ignore_zones the zone is ignored in the CI and locally when operators run trackbone manually.

Since the field value is a default value (*true) it is possible to override it locally in some other file which is not committed in the git repo.

For example if we declare in envs.cue:

ignore_zones: "ocb-test01": _

It is ignored locally and in the ci:

 cue eval -t in_ci -t staging -e 'list.Contains([for n, _ in envs {n}], "ocb-test01")'
false
 cue eval -t staging -e 'list.Contains([for n, _ in envs {n}], "ocb-test01")'
false

Now the operator has still the possibility to use the zone by creating a file like:

 cat <<EOF > local.cue
package terraform

ignore_zones: "ocb-test01": false
EOF

This way it doesn't ignore the zone locally anymore:

 cue eval -t staging -e 'list.Contains([for n, _ in envs {n}], "ocb-test01")'
false

Still it is also possible to edit manually envs.cue to unignore the zone locally but by doing that there is a chance to commit inadvertently the change in the repo since the file is tracked by git.