Add support for pass/drop/tagpass/tagdrop for outputs

[oldmantaiter]

Reuses a lot of the logic for the plugin configuration, and changed
the ConfiguredPlugin struct to be ConfiguredFilter and a generic
function to parse the filter (called parseFilter).

X-Github-Closes #398

[oldmantaiter]

@sparrc Still need to write additional tests, but wanted to see if this is what you had in mind. This version is working to filter both tags and measurements by prefix.

[sparrc]

@oldmantaiter sorry I should have warned you earlier that I had some large agent/config changes coming. This may be very difficult to rebase but give it your best shot and let me know if you have any questions.

[oldmantaiter]

@sparrc No problem, I'll fix up

[sparrc]

I don't like overloading this, I would prefer if we kept PluginConfig and add another struct called just Filter that can be part of PluginConfig. Then probably will need to add an OutputConfig struct as well

[sparrc]

Or if Name & Interval aren't being used from here (I'm not sure if they are?), remove them and just call this struct Filter

[sparrc]

Any reason you made these non-pointer receivers? (Filter instead of *Filter)

[sparrc]

Thanks a bunch @oldmantaiter! This looks really good, just the one comment about non-pointer receivers and then I'll work on getting this merged

[oldmantaiter]

@sparrc Thanks! The non-pointer in Filter is really just for the tests (they fail with a pointer because of inequality)

EDIT: I misread your comments, it was basically to keep from reference/de-reference because the tests required the struct and not a pointer to it to pass.. if that makes sense?

[sparrc]

good idea 👍

[sparrc]

@oldmantaiter, cool, that makes sense, do you have any more changes or is this PR ready to merge?

[sparrc]

thanks @oldmantaiter! This will be in release 0.2.4

[oldmantaiter]

@sparrc Didn't see the previous question, ran it for a couple hours on my local testing environment with the options enabled and did not see any issues so it is good to go. Thanks!