[Wizard] Add the ability to invoke OnFinish

[StevenRasmussen]

Pull Request

📖 Description

The FluentWizard currently allows you to customize the ButtonTemplate which is great! And there is a public method exposed (GoToStepAsync) which allows you to essentially call the Next and Previous buttons manually from your custom buttons. However, there is no way to call the OnFinish logic from a custom button. This updates the component to expose a new method called FinishAsync with an optional parameter to validate the form contexts (which I modeled after the GoToStepAsync method).

I am not sure if/how you would like me to add unit tests for this. There are not any unit tests currently for the 'Customized' ButtonTemplate portion of the FluentWizard. I ran all the current unit tests to ensure that nothing broke. If you would like a unit test added, please specify what the unit test should be doing so that I know how you would like it written and what it would be testing.

👩‍💻 Reviewer Notes

I have updated the demo site page to include a new Finish button on the "Customized Wizard" area.

✅ Checklist

General

• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

Component-specific

• I have added a new component
• I have added Unit Tests for my new component
• I have modified an existing component
• I have validated the Unit Tests for an existing component

[dvoituron]

That could be a good additional method.

For the Unit Tests, you need take inspiration from FluentWizard_EditForm_EditContextIsInValid_OnNext, FluentWizard_EditForm_EditContextIsInValid_OnFinish(), FluentWizard_EditForm_EditContextIsValid and to create a new test including the ButtonTemplate

[StevenRasmussen]

@dvoituron - I've added the following 3 unit tests as requested: FluentWizard_CustomizedButtonTemplate_EditForm_EditContextIsInValid_OnNext, FluentWizard_CustomizedButtonTemplate_EditForm_EditContextIsInValid_OnFinish and FluentWizard_CustomizedButtonTemplate_EditForm_EditContextIsValid.