I do this a lot:

```erb
<%= select :post, :author, authors, required: true %>
```

It doesn't work; the `required` attribute is ignored! Instead, you need to do this:

```erb
<%= select :post, :author, authors, {}, required: true %>
```

It's hard to remember the right API, and it looks to me like a code smell. It looks even smellier when you end up with this:

```erb
<%= select :post, :author, authors, { include_blank: "Choose an option" }, { required: true } %>
```

Where this would be nicer, but again, the `required` attribute is ignored:

```erb
<%= select :post, :author, authors, include_blank: "Choose an option", required: true %>
```

This PR implements a special handling for `required`, `multiple`, and `size` HTML attributes so that these now do the same thing:

```erb
<%= select :post, :author, authors, include_blank: "Choose an option", required: true %>
<%= select :post, :author, authors, { include_blank: "Choose an option" }, { required: true } %>
```

ps. as proof I'm not the only person who makes this mistake, one of the tests in the Rails test suite was wrong! The test added in https://github.com/rails/rails/pull/40522 puts the `multiple` attribute in the wrong place and has the wrong assertion as as result. This PR includes a fix for the test.