fix(dynamic): enable form options with any generic type

[ChrisRx]

Hi! PR #233 introduced dynamic options to be used in forms and initially I was unable to get the following example working:

	var workspaceId, folderId int
	form := huh.NewForm(
		huh.NewGroup(
			huh.NewSelect[int]().
				Title("Choose your workspace").
				Height(15).
				Options(options...). // initial options constructed from API call
				Value(&workspaceId),
			huh.NewSelect[int]().
				Value(&folderId).
				Title("Choose your folder").
				Height(5).
				OptionsFunc(func() (options []huh.Option[int]) {
					if workspaceId == 0 {
						return
					}
					// API call using workspace ID to fetch list of folder ids
					return
				}, &workspaceId),
			huh.NewConfirm().
				Title("Use selected?").
				Value(&proceed),
		),
	)

but I was able to get the examples included in the PR working. Digging further I was able to get my example working using huh.Option[string] and the issue ended up being this particular type switch not matching the generic type huh.Option[int]:

huh/group.go

Lines 251 to 261 in ccca06d

	switch msg := msg.(type) {
	case spinner.TickMsg,
	updateTitleMsg,
	updateDescriptionMsg,
	updateSuggestionsMsg,
	updateOptionsMsg[string],
	updatePlaceholderMsg:
	m, cmd := g.fields[i].Update(msg)
	g.fields[i] = m.(Field)
	cmds = append(cmds, cmd)
	}

I tried bumping the project to Go 1.20 and adding UpdateOptionsMsg[any] to the switch case, but that didn't work, so instead I made the isUpdateOptionsMsg interface and embedded it in UpdateOptionsMsg. I'm unsure if this is the best approach but it does seem to work and I couldn't find in my searching if there is a more intended way to solve this in Go.

[maaslalani]

Hey @ChrisRx, thanks so much for this PR. I've fixed this issue in #318. Let me know if this works for you!