Allow overriding button_to_generates_button_tag per-invocation

ref: rails#40747

The global config is great for new projects, but for large existing projects, auditing every `button_to` call could be overwhelming enough to not bother.

This PR allows you to set if a button should always be returned per-invocation. This way you can gradually opt in to the config, or you can use it only in parts of your codebase.

```ruby

button_to("Save", "http://www.example.com") # renders <input>
button_to("Save", "http://www.example.com", button_tag: true) # renders <button>
button_to("Save", "http://www.example.com", button_tag: false) # renders <input>

button_to("Save", "http://www.example.com") # renders <button>
button_to("Save", "http://www.example.com", button_tag: true) # renders <button>
button_to("Save", "http://www.example.com", button_tag: false) # renders <input>
```

actionview/CHANGELOG.md

@@ -1,3 +1,21 @@
+*   `button_to` now accepts a `button_tag:` option, to override the `button_to_generates_button_tag` config
+
+    ```ruby
+    # With config.action_view.button_to_generates_button_tag = false
+
+    button_to("Save", "http://www.example.com", button_tag: true) # renders <button>
+    button_to("Save", "http://www.example.com", button_tag: false) # renders <input>
+    button_to("Save", "http://www.example.com") # renders <input>
+
+    # With config.action_view.button_to_generates_button_tag = true
+
+    button_to("Save", "http://www.example.com", button_tag: true) # renders <button>
+    button_to("Save", "http://www.example.com", button_tag: false) # renders <input>
+    button_to("Save", "http://www.example.com") # renders <button>
+    ```
+
+    *Alex Ghiculescu*
+
 *   Don't double-encode nested `field_id` and `field_name` index values
 
     Pass `index: @options` as a default keyword argument to `field_id` and

actionview/lib/action_view/helpers/url_helper.rb

@@ -274,6 +274,13 @@ def link_to(name = nil, options = nil, html_options = nil, &block)
       #   #      <input name="authenticity_token" type="hidden" value="10f2163b45388899ad4d5ae948988266befcb6c3d1b2451cf657a0c293d605a6"/>
       #   #    </form>"
       #
+      # By default, `config.action_view.button_to_generates_button_tag` is `true`, and a `<button>`
+      # is always returned. If `config.action_view.button_to_generates_button_tag` is `false`, an `<input>`
+      # will be returned if a block is not given. To set this per-invocation, pass the `button` option:
+      #
+      #   <%= button_to "New", new_article_path, button: true %> # Renders a button
+      #   <%= button_to "New", new_article_path, button: false %> # Renders an input
+      #
       # Most values in +html_options+ are passed through to the button element,
       # but there are a few special options:
       #
@@ -387,12 +394,13 @@ def button_to(name = nil, options = nil, html_options = nil, &block)
           ""
         end
 
+        use_button = html_options.key?("button_tag") ? html_options.delete("button_tag") : button_to_generates_button_tag
         html_options = convert_options_to_data_attributes(options, html_options)
         html_options["type"] = "submit"
 
         button = if block_given?
           content_tag("button", html_options, &block)
-        elsif button_to_generates_button_tag
+        elsif use_button
           content_tag("button", name || url, html_options, &block)
         else
           html_options["value"] = name || url

actionview/test/template/url_helper_test.rb

@@ -402,6 +402,18 @@ def test_button_to_generates_input_when_button_to_generates_button_tag_false
     ActionView::Helpers::UrlHelper.button_to_generates_button_tag = old_value
   end
 
+  def test_button_to_generates_button_when_button_to_generates_button_tag_false_but_argument_is_provided
+    old_value = ActionView::Helpers::UrlHelper.button_to_generates_button_tag
+    ActionView::Helpers::UrlHelper.button_to_generates_button_tag = false
+
+    assert_dom_equal(
+      %{<form method="post" action="http://www.example.com" class="button_to"><button type="submit">Save</button></form>},
+      button_to("Save", "http://www.example.com", button_tag: true)
+    )
+  ensure
+    ActionView::Helpers::UrlHelper.button_to_generates_button_tag = old_value
+  end
+
   def test_button_to_with_content_exfiltration_prevention
     with_prepend_content_exfiltration_prevention(true) do
       assert_dom_equal(