Please include operators to help with debugging

[goetzk]

Is your feature request related to a problem? Please describe

This was discussed in the pyinfra chat at the start of February but doesn’t look like it was ever requested on the record.

Quoting members of the chat:
"One other thing I'd love to see is some easier way besides the callback dance to get output either while a command is running, or immediately following the command; in Ansible the typical way was to run a command, register a variable, and then use the 'debug' module to dump it to screen. (Maybe there is an easier way but right now i'm using callbacks)"

"Sounds like pyinfra needs some debug.* operations which are basically callbacks to print command outputs/etc as part of the operation flow 🤔 (That was @Fizzadar )

Describe the solution you'd like

A builtin way to check the content/state of a previously registered tasks output.