Add flowdrop_workflow_executor module infrastructure
>>> [!note] Migrated issue
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<!-- Migrated from issue #3571278. -->
Reported by: [joevagyok](https://www.drupal.org/user/2876343)
>>>
<h3>Summary</h3>
<p>Add the <code>flowdrop_workflow_executor</code> module that provides infrastructure for executing FlowDrop workflows from within other workflows. This module bundles the Workflow Executor node, Results Retriever node, execution service, and queue worker.</p>
<h3>Module Dependencies</h3>
<ul>
<li><code>flowdrop:flowdrop</code> - Core FlowDrop module</li>
<li><code>flowdrop:flowdrop_workflow</code> - Workflow entity support</li>
<li><code>flowdrop:flowdrop_playground</code> - Session-based execution</li>
</ul>
<h3>Provided Services</h3>
<ul>
<li><code>flowdrop_workflow_executor.service</code>: Main workflow execution service</li>
</ul>
<h3>Provided Plugins</h3>
<ul>
<li><code>flowdrop_workflow_executor:workflow_executor</code>: Execute child workflows</li>
<li><code>flowdrop_workflow_executor:workflow_results_retriever</code>: Retrieve async results</li>
</ul>
<h3>Queue Workers</h3>
<ul>
<li><code>workflow_executor_queue</code>: Process fire-and-forget executions</li>
</ul>
<h3>Configuration Entities</h3>
<p>Includes node type configurations for both processors with appropriate parameter and output configurations.</p>
issue