Support config for fetcher and parser plugins

This doesn't have any changes to the processor settings. Those will be more complicated and it's already past midnight here.

The schema in the patch in #2 contains the new parser setting that I was adding for 🐛 Prevent post-dated posts from staying at the top of aggregated feeds Needs review . I forgot to remove it.

The last submitted patch, 2: 3389441-2.patch, failed testing. View results →
- codesniffer_fixes.patch Interdiff of automated coding standards fixes only.

I think there may be one or two more test failures to fix after this. The D7 settings migration is being weird.

The last submitted patch, 6: 3389441-6.patch, failed testing. View results →
- codesniffer_fixes.patch Interdiff of automated coding standards fixes only.

This should fix the last failure.

It may be best to not deal with reconfiguring the processors in this issue. As I've discovered, the rabbit hole only goes deeper once you start messing with them.

Notes:

• This is a BC break. It's possible that someone is using the config values in their current locations. Moving them can break existing custom code. So unfortunately this needs to wait if we want to do things properly.
• There's a lot of duplication going on in the schema. I didn't think about it much until I started working on the processors last night and I was adding even more. It might be more efficient to have an aggregator_plugin schema type and then try to sub-type that. Also, the settings schemas are the same because they're all simple mappings. I was mostly started doing this because our default fetcher, parser, and processor plugins are all named aggregator. So I had to come up with a way of ensuring there weren't name collisions.

One thing we could do here to smooth over the BC issue it is move to an aggregator type. Which is a config entity

It has a plugin bag for each of the plugin types which keeps the ID and configuration

Then the settings is deprecated.

And we put a aggregator type bundle on the Feed entity type.

This would bring it in line with how these things normally work in core.

i.e. Plugin configuration goes in plugin bags on config entities

And then the aggregator settings are largely not used anymore

At that point we're starting to look a lot like a competitor to feeds module though.