To achieve this we hook in at the beginning of our custom `HelpFunc` and detect
the plugin case by adding stub commands.
Signed-off-by: Ian Campbell <ijc@docker.com>
To do this we add a stub `cobra.Command` for each installed plugin (only when
invoking `help`, not for normal running).
This requires a function to list all available plugins so that is added here.
Signed-off-by: Ian Campbell <ijc@docker.com>
To help with this add a bad plugin which produces invalid metadata and arrange
for it to be built in the e2e container.
Signed-off-by: Ian Campbell <ijc@docker.com>