ViewComponents only supports one variant

[sfnelson]

Steps to reproduce

Render an action that includes multiple variants. For example: :app and :admin.

request.variant << :app if request.user_agent&.include?("Hotwire Native")
request.variant << :admin if Current.admin.present?

Set up a situation where a view component uses the second variant (:admin).

Expected behavior

The template for the admin variant should render for admin requests from web and from turbo native.

Actual behavior

The default template renders for turbo native admin requests, while the admin template correctly renders for web requests.

System configuration

Rails version:
7.1.4

Ruby version:
3.3.5

Gem version:
3.18

Notes

This issue is caused by an assumption in ViewComponents::base#render_in that there will only be one variant. This is not a correct assumption.

# For template variants (+phone, +desktop, etc.)
@__vc_variant ||= @lookup_context.variants.first

I'm planning to add a test to the work I'm doing for #2128 and resolve the issue by using Rails' logic to pick the preferred variant.