Add shortcuts to import/export Rules

Committed.

Yes, that sounds useful, but I don't want to contaminate a core administration page with Rules-specific stuff for everyone to see every time they visit that page. Is there a way instead to append a ?destination= argument when clicking on the action link on the Rules page, that way when the config import/export form is submitted it will redirect back?

The first Drupal 8 release was more than 7 years ago. Yet I defy anyone to show me documentation on drupal.org, either API documentation or other core documentation, which describes the keys available for use in *.links.action.yml, let alone describes how to use these keys. This is just one example of the total failure of Drupal to provide basic documentation for its foundational core APIs.

But here's a secret - the *.links.action.yml file accepts TWO undocumented keys, 'route_parameters' and 'options'. Core never uses these anywhere, so there are no examples. And these are not described in the hook documentation for altering local actions, nor in the documentation for *.links.action.yml, nor in the documentation for LocalAction or LocalActionManager, or anywhere else I have found. You just have to know that *.links.action.yml holds YML annotation for discovery of LocalAction type plugins, and then you have to read the code. Just like many things in Drupal.

For this issue, we can use the undocumented 'options' key to put the destination into the *.links.action.yml file like this:

# Shortcut to import Reaction Rule / Rules Component.
rules_import_action:
  route_name: config.import_single
  options:
    query:
      - destination: admin/config/workflow/rules
  title: 'Import rule'
  appears_on:
    - entity.rules_reaction_rule.collection
    - entity.rules_component.collection

In the attached patch I split this up and create separate actions for the Reaction Rule list builder and the Rules Component list builder so they don't redirect back to the same place.

Regardless, this seems to work the way we want it for the import case, even with the confirm form in the way. For the export case, the export form doesn't have any button, so there's never any action to trigger the redirect.

Rearranging the lines - I think it's more readable to list the title first. This patch is otherwise identical to #9.

I feel this is really a problem with the core Configuration Export page, as the UI for that has always been very strange - it outputs the exported configuration in a textarea, and presents a description of what you should name the file if you cut/paste the contents of that textarea. Not sure why cut/paste is the preferred (and only) form of "export" here, as cut/paste should really only be a fallback / last resort for dealing with bulk data.

I don't know what the use case for the current page is, but I think it would be much better if there were a download button which would initiate a download when you selected a configuration to export (and BTW would set the file name appropriately for you ...). This could be in addition to the textarea OR as a replacement for the textarea, but I don't see how the cut/paste model is useful, other than to inspect the contents of the config - but that use case is not really related to "exporting" configuration, and that use case is better handled by the Config Inspector module.

So I think maybe we should just commit #10 without trying to redirect back from the export page, but we should also open up a core issue with a proposal to fix the config export page to be something more useful. Then after core is fixed we can patch Rules to redirect back from that more-useful export page since it will now have a button.

Updated issue summary.

With any luck we won't need to patch, as the destination will already be set with this commit. Obviously it depends on the the exact UI process implemented

Oh, that's true isn't it. OK, that's even better.

Committed #10.