* feat(api): add --json flag as no-op alias for --format json
* feat(service): add --json flag as no-op alias for --format json
* feat(shortcut): add --json flag as no-op alias for --format json
Skip registration when a custom --json flag already exists on the
command (e.g. base shortcuts use --json for body input).
Change-Id: If66236cadeea7fa81811061cce775deff51b92ce