Issue #2832601 by dpi: Incoming messages handling tweaks and stricter model enforcement

This commit includes breaking changes, see the change record for more info: https://www.drupal.org/node/2836073

Enforce result and reports and added plugin incoming event
Fixed failing tests
Added results and reports for incoming messages created in tests.
Added createMessageResult test helper to create reports and result for a message.
Fixed failing tests due to missing reports
Test coverage for new result/report exceptions
Compacted sms_test_gateway gateway config schema (Derivative types)
Added plugin incoming method to execution order tests.
New test file covering \Drupal\sms\EventSubscriber\SmsMessageProcessor (some \Drupal\Tests\sms\Kernel\SmsFrameworkProviderTest tests should be moved there)
Added supports incoming messages gateway annotation property.
Added SmsGateway::supportsIncoming()
Add preprocess check to incoming messages ensuring they have a gateway set, and the gateway supports incoming messages.
Added tests for above.
Added missing gateway entity to incoming message tests.