Expose IncludeGenerated in CodeFormatterOptions

[Vhab]

Environments:

• CSharpier Version: 0.27.3
• Running CSharpier via: API
• Operating System: Windows
• .csharpierrc Settings: N/A
• .editorconfig Settings: N/A

We would like to use CSharpier to format generated code before writing it.
Our generated code includes the <auto-generated> header causing CSharpier to skip it.
It would be nice for IncludeGenerated to be added to CodeFormatterOptions to disable this behavior.

[belav]

Sounds totally reasonable!