Parallel Execution & Add ability to push variables to scheduled work

[sfmskywalker]

=== auto-pr-body ===

Summary:

• Refactored several methods to improve readability and performance
• Removed redundant using statements in multiple classes
• Replaced multiple usings with Elsa.Workflows.Runtime related usings where applicable
• Added a dynamicVariables property to ActivityExecutionContextState class
• Updated CreateActivityExecutionContext and CreateActivityExecutionContextState to support dynamicVariables
• Removed unused using statements across multiple classes

Suggested Refactoring/Modifications:

• Consolidate common methods into a single class, if applicable
• Add missing using statements in applicable classes where needed
• Separate out redundant calls to simplify code
• Add headers to classes to describe purpose and function
• Update variable and parameter names for enhanced readability