Add Variable Name Validation and Wrapper Control

[sfmskywalker]

This PR adds an option to disable the automatic wrapper generation of C# and JavaScript functions for workflow variables.

Changes:

• C# Syntax:
  When opting out, Variables.MyVariable will no longer be available. Variables can only be accessed using:

  • Variables.Get("MyVariable")
  • Variables.Get<T>("MyVariable")

  Configuration:
  To disable wrappers in C#, use the following configuration:

  elsa.UseCSharp(options =>
  {
      options.DisableWrappers = true;
  });

• JavaScript Syntax:
  When opting out, variables.MyVariable and getMyVariable() will no longer be available. Variables can only be accessed using:

  • getVariable("MyVariable")

  Configuration:
  To disable wrappers in JavaScript, use the following configuration:

  .UseJavaScript(options =>
  {
      options.DisableWrappers = true;
  });

Use Case:

This feature is helpful for applications requiring the use of variable names that are invalid in JavaScript or C#.

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This change is