fix: json target when combined with scm

[olblak]

While investigating #1590 (comment)

I discovered that the json target plugin combined with a scm was broken.
It's scenario difficult to test so I missed when for some reason the plugin stops returning the list of files to commit.

I also took the opportunity to apply the following improvement

• When updating files, we now show each description, one per line
• When used with a scm, the log output see the original file and

Test

To test this pull request, I used the following manifest

scms:
  default:
    kind: github
    spec:
      owner: updatecli-test
      repository: kwctl
      branch: main
      token: '{{ requiredEnv "GITHUB_TOKEN"}}'
      username: "olblak"
      user: '{{ requiredEnv "GITHUB_ACTOR"}}'
      email: "me@olblak.com"

sources:
  default:
    kind: jenkins

targets:
  default:
    name: "Update rebaseWhen"
    kind: json
    scmid: default
    spec:
      file: "renovate.json"
# Enable to test that the file was modified
      key: "rebaseWhen"
# Enable to test that the file wasn't modified
#      value: "behind-base-branch"

and

go build -o bin/updatecli .
./bin/updatecli apply --config /tmp/updatecli.yaml --push=false

then I checked in /tmp/updatecli/github/updatecli-test/kwctl/ that I had a commit with the file changed

Additional Information

Tradeoff

Potential improvement

While I am in this plugin, I need to double check the csv plugin and the toml one as they also rely on dasel
Just by looking at the code they seems to be fine