This change:

• Revamps the existing Input and FieldInput components
• Revamps the existing Select* and FieldSelect* family of components, including unifying the set of accepted properties and supported features between the components of the family
• Replaces the concept of "label tooltip" with "helper text" to better align with the UX dictionary and the actual placement of the helper text
• Tweaks the existing UI in necessary places.

Figma: inputs, dropdowns

This is a large PR, so it's best to review it commit by commit. I decided to lump both input and select changes together, since they frequently appear together and testing these changes together saved a lot of time.

Caveats:

• I took liberty to implement a small size for the select control, even though it wasn't designed, for consistency with inputs (and there was at least one place that required it).
• There's still a separate implementation of SelectCreatable inside teleport/Discover/Shared/SelectCreatable, but I don't want to make this PR bigger than it already is.

Fixes #46611
Needs to be merged together with https://github.com/gravitational/teleport.e/pull/5052.

Tested by inspecting all storybook entries and making sure that layouts are fine and don't break when they show validation errors. A couple of screens were also tested on the real Web and Connect UI.

Note: since this PR is the largest and latest of the highly-visible UI changes, it bears the changelog line; however, this has been gradually introduced to v17 across a multitude of PRs. To see the entire development history, see all subissues of #37260.

Changelog: Refreshed the Web and Teleport Connect UI design.