fix: add form submission and reset behavior to Button

[nicholasrice]

Description

#3534 describes an issue where a FASTButton[type=submit] does not actually submit the parent form. In fixing this, I also noticed that a FASTButton[type=reset] does not reset the form. This introduces a fix to both behaviors.

A FASTButton[type=reset] will simply invoke the reset() method of the associated form element when clicked.

Submission behavior is a bit more complicated. The FASTButton[type=submit] will try to use the requestSubmit() method of the form if it exists, supplying the method with the button's proxy element as the submitting element (see #3534) for more info. If the requestSubmit() method is unavailable (Safari) then the proxy's click() method will be invoked.

closes #3534

Motivation & context

Issue type checklist

• Chore: A change that does not impact distributed packages.
• Bug fix: A change that fixes an issue, link to the issue above.
• New feature: A change that adds functionality.

Is this a breaking change?

• This change causes current functionality to break.

Adding or modifying component(s) in @microsoft/fast-components checklist

• I have added a new component
• I have modified an existing component
• I have updated the definition file
• I have updated the configuration file

Process & policy checklist

• 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.