Issue #1930274 by rootatwc, Berdir: Convert aggregator processors and parsers to plugins.

core/modules/aggregator/aggregator.admin.inc

core/modules/aggregator/aggregator.api.php

core/modules/aggregator/aggregator.module

core/modules/aggregator/aggregator.parser.inc

core/modules/aggregator/aggregator.processor.inc

...les/aggregator/lib/Drupal/aggregator/AggregatorBundle.php

...ggregator/lib/Drupal/aggregator/FeedStorageController.php

.../lib/Drupal/aggregator/Plugin/AggregatorPluginManager.php

...regator/lib/Drupal/aggregator/Plugin/FetcherInterface.php

...gregator/lib/Drupal/aggregator/Plugin/ParserInterface.php

...gator/lib/Drupal/aggregator/Plugin/ProcessorInterface.php

...l/aggregator/Plugin/aggregator/fetcher/DefaultFetcher.php

...pal/aggregator/Plugin/aggregator/parser/DefaultParser.php

...gregator/Plugin/aggregator/processor/DefaultProcessor.php

...b/Drupal/aggregator/Tests/AggregatorConfigurationTest.php

...egator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php

...tor/lib/Drupal/aggregator/Tests/FeedFetcherPluginTest.php

...r/lib/Drupal/aggregator/Tests/FeedProcessorPluginTest.php

...egator/lib/Drupal/aggregator/Tests/UpdateFeedItemTest.php

...ules/aggregator/tests/config/aggregator_test.settings.yml