Every `:report` subcommand now recognizes `--global` as a scope selector that limits the report to globally-configured properties, including in JSON form via `--global --format json`. Previously this combination was rejected because `--global` was treated as an info flag, conflicting with `--format`. The shared `common.ParseReportArgs` helper now returns a `ReportArgs` struct exposing the parsed scope; each Go and bash report selects a global-only flag map when scope is global, and skips per-app verification.
The previous lever for manipulating this was the DOKKU_IMAGE environment variable. While this is all well and good, it only works for CNB and is yet another `DOKKU_*` environment variable that need not exist.
While this does not add support for manipulating the CNB stack just yet, the groundwork is set for the future.
Closes#4306
