Add context to action processing

[thenbrent]

Add context to action processing / queue runners so that we can log where the action are run from, e.g. WP CLI, WP Cron the Admin List Table or the upcoming Async Runner.

Very handy for debugging issues after the fact.

Example logs entries: https://cld.wthms.co/fT0T96

Fixes #129

[rrennick]

If we did the context as a slug => Name then the slug could be used by hooks and the Name would be translatable for messages/output. The context array could be stored so only the slug needed to be passed.

[thenbrent]

I looked at making the context available for translation, but it's a proper noun in most cases - WP CLI, WP Cron - and pretty close to a proper noun in others - Admin List Table and Async Request - so I decided to instead leave it out of translation.

Are there any benefits to using slugs elsewhere? e.g. wp_cron instead of 'WP Cron' (other than avoiding strings in places you might not expect whitespace).

The context array could be stored so only the slug needed to be passed.

We'd also need to make sure it's got a filter.

[rrennick]

I looked at making the context available for translation, but it's a proper noun in most cases

That sounds good.

Some of the unit tests need to be updated for message string changes.

[thenbrent]

Some of the unit tests need to be updated for message string changes.

@rrennick fixed. 👍

[rrennick]

@thenbrent LGTM. There is a merge conflict on hook parameter numbers. Once those are fixed this should be okay to merge.

[thenbrent]

Thanks @rrennick. I've rebased in a fix for the merge conflict.