fix: formassociated and async tests on firefox

[radium-v]

Description

• fix broken FormAssociated tests on Firefox
• make sure tests are asynchronous and that each scenario cleans up after itself
• fix a select test that was incorrectly using native browser elements

Motivation & context

All of the FormAssociated tests were working in Chromium but failing in Firefox. There were also some tests that used timeouts and others that didn't utilize async fixture methods. Tests can use the fixture's parent and document to attach elements like forms when needed, and all fixture-based tests should call disconnect() or remove any attached elements at the end of each scenario.

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.

[EisenbergEffect]

Thanks for putting the work into this! Is there anything you think we can do to improve our test helpers to guide folks into the pit of success in the future? I'm hoping to pull the test helpers out into their own package for community use in the not distant future. We can certainly add docs around these things but I'm wondering if we can make the helpers better as well.

[EisenbergEffect]

Nice!

[radium-v]

@EisenbergEffect I think documenting a scenario's cycle (setup, connect, test, disconnect) will be super useful, and making sure that components have general guidelines for what needs to be tested will go a long way for coverage. Just a few different types of tests I'm commonly seeing for our components are connection/disconnection, attributes, properties, user interaction, and form association.

[nicholasrice]

Awesome to see this!