Add 'add block' button to blocks field#487

The blocks field currently has no directly clickable button to add blocks. You have to either click the three dots at the top, or select a block and then click the plus sign. This is not always intuitive. It’s also not consistent with the layout field, which does have a little plus button at the bottom.

I imagine a simple button at the bottom of the field would help improve the UX. I have included a little mockup to clarify the idea.