feat: add stealth appearance to fluent-select

[RehanSaeed]

🙋 Feature Request

I'd like the fluent-select to have a stealth appearance.

🤔 Expected Behavior

There should be no border around the component and a stealth background colour should be added on hover.

😯 Current Behavior

There is no appearance attribute like some other components have.

[EisenbergEffect]

/cc @bheston for consideration.

[chrisdholt]

/cc @bheston for consideration.

This is probably also a larger "fluent" conversation. I think one possible issue here could be WCAG requirements for inputs and controls - definitely something to look at as we consider.

[bheston]

The request is for fluent-select but this came in under FAST. I want to confirm the is for Fluent. The 'stealth' appearance is one of the new select appearances, so I've added it to my open styling PR microsoft/fluentui#19263.

FAST still doesn't have support for appearances on Select, which I think would be beneficial. Leaving this open for a bit for anyone in the community to comment until we get a chance to restyle the FAST controls.

[RehanSaeed]

I raised this for:

import { FluentSelect } from @fluentui/web-components;