Added a view path fallback handling.

[Jack12816]

ActionView::MissingTemplate in FactoryBot::Instrumentation::Root#index
Showing /usr/local/bundle/gems/factory_bot_instrumentation-1.1.1/app/views/factory_bot/instrumentation/root/index.html.erb where line #23 raised:

Missing partial factory_bot/instrumentation/root/_spinner, application/_spinner with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:raw, :erb, :html, :builder, :ruby]}. Searched in:
  * "/app/app/views"
  * "/usr/local/bundle/gems/administrate-0.16.0/app/views"
  * "/usr/local/bundle/gems/factory_bot_instrumentation-1.1.1/app/views"
  * "/usr/local/bundle/gems/kaminari-core-1.2.2/app/views"
  * "/usr/local/bundle/gems/grape-swagger-rails-0.3.1/app/views"

For some reason the "factory_bot/instrumentation/root/_spinner" is searched for, not "factory_bot/instrumentation/application/_spinner" as expected in this case.