Always generate <button> tags with button_to

In Rails 6.1 and earlier, `button_to` generated a <button> tag when it
received the content as a block, but an <input> tag when receiving
the content as the first parameter.

That's why we were using blocks with `button_to` most of the time; for
starters, <button> tags accept pseudocontent and so are easier to style.

In Rails 7.0, `button_to` always generates a <button> tag [1], so we're
simplifying the code what uses `button_to`, passing the content as a
first parameter instead of passing it as a block.

[1] https://guides.rubyonrails.org/v7.1/configuring.html#config-action-view-button-to-generates-button-tag

config/initializers/new_framework_defaults_7_0.rb

@@ -11,7 +11,7 @@
 
 # `button_to` view helper will render `<button>` element, regardless of whether
 # or not the content is passed as the first argument or as a block.
-# Rails.application.config.action_view.button_to_generates_button_tag = true
+Rails.application.config.action_view.button_to_generates_button_tag = true
 
 # `stylesheet_link_tag` view helper will not render the media attribute by default.
 # Rails.application.config.action_view.apply_stylesheet_media_default = false