Fluid inputs: remove from experimental, mark as stable

[tay1orjones]

Fluid Inputs were delivered in https://github.com/carbon-design-system/carbon/issues/5416 behind an experimental/unstable flag.

We should consider moving these to stable after we've received feedback on the components, their API, usage docs, styling, etc.

- [ ] Consider if we have any changes we need to make to these components based on feedback during the experimental period
- [ ] If ready, review [the documented "Moving to stable" checklist](https://github.com/carbon-design-system/carbon/blob/main/docs/experimental-code.md#moving-to-stable) that outlines what must be done to move these components to stable
- [ ] Add a11y and VRT tests for them now that we can use controls in the visitStory() function for e2e tests.
- [ ] Copy that checklist into this issue (when ready to work on this)
- [ ] Make any changes as necessary to fluid input components (based on the checklist)
- [ ] Announce stability in changelog and slack blasts after release
- [ ] https://github.com/carbon-design-system/carbon/issues/17196
- [ ] https://github.com/carbon-design-system/carbon/issues/16809
- [ ] https://github.com/carbon-design-system/carbon/issues/16938
- [ ] https://github.com/carbon-design-system/carbon/issues/16939

[tay1orjones]

Marked as blocked and needs more info because we won't be moving these to stable until they've been published for a while and we've received feedback on these components.

If there's not been any feedback for changes needed for a while, we can consider this issue to move them to stable.

[tay1orjones]

We might want to consider waiting for https://github.com/carbon-design-system/carbon/issues/13682 to land before we mark these stable

[tay1orjones]

There's no longer a hard blocker on this one. Converting it to an umbrella issue as there's quite a few moving pieces to complete here.