feature #24751 [Workflow] Introduce a Workflow interface (Simperfit)

This PR was merged into the 4.1-dev branch.

Discussion
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[Workflow] Introduce a Workflow interface

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | #23910
| License       | MIT
| Doc PR        | todo

@chalasr I think all the points you made in 23910 has been done. Needs to update the docs too.

Commits
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e8351d8 [Workflow] Introduce a Workflow interface

Author: lyrixx

DependencyInjection/FrameworkExtension.php

@@ -498,7 +498,7 @@ private function registerWorkflowConfiguration(array $config, ContainerBuilder $
             // Add workflow to Registry
             if ($workflow['supports']) {
                 foreach ($workflow['supports'] as $supportedClassName) {
-                    $strategyDefinition = new Definition(Workflow\SupportStrategy\ClassInstanceSupportStrategy::class, array($supportedClassName));
+                    $strategyDefinition = new Definition(Workflow\SupportStrategy\InstanceOfSupportStrategy::class, array($supportedClassName));
                     $strategyDefinition->setPublic(false);
                     $registryDefinition->addMethodCall('add', array(new Reference($workflowId), $strategyDefinition));
                 }