debug-hooks doesn't accept a named action

[Adam Israel]

Version: Juju 2.0.x

The `debug-hooks` command does not work if an action is named, similar to a hook, i.e.,:

$ juju debug-hooks netutils/1 dig
ERROR unit "netutils/1" does not contain hook "dig"

Naturally, this is because dig is an action, not a hook, but actions run in a similar context. If I were to simply run:

$ juju debug-hooks netutils/1

and in a different terminal:
$ juju run-action netutils/1 dig

The debug-hooks session opens in the context of the action, where the action can be debugged. This is an ugly workaround, though, because by hooking all events in the charm, you may have to cycle through the queue of hooks (update-status, config-changed, leader-elect, etc) before the action is run. This leads to a poor developer experience.

I propose two possible solutions:

a) allow the debug-hooks command to accept a hook name
or
b) add a debug-actions command that works similar to debug-hooks but only accepts action names.

[Merlijn Sebrechts (merlijn-sebrechts)]

Note that this _is_ documented as a working feature:

https://jujucharms.com/docs/stable/developer-debugging

```
To debug actions, you use the same command, like this:

juju debug-hooks <service/unit> [action-name action-name2 ...]
For example, if you want to check the add-repo action of a the git charm, use:

juju debug-hooks git/0 add-repo
Learn more about actions in Juju actions.
```

Please update the docs to remove that feature, if this is truly a "wishlist" item.

[Anastasia (anastasia-macmood)]

PR against develop: https://github.com/juju/juju/pull/8081