This issue is the result of a long and good discussion in #3785, which this issue subsumes.

Right now the toolbar across text blocks change a fair bit, and in the case of the heading block, it's not possible to set the alignment unless you open the sidebar. Let's simplify and unify that:

A toolbar for text-blocks consists of these elements and in this order:

1. The block switcher. This doubles as a block type indicator, even when a block has no transformations.
2. An optional "level selector". For headings, this lets you select the level of the heading. For the list block, this lets you pick between the type of list.
3. Text alignments. This one can collapse.
4. Inline formatting. Don't put any buttons here that apply on the block level, it's inline-only.
5. More menu.

A few other details in this mockup:

• The More menu button has been made thinner, as the vertical icon affords this.
• The dropdown triangle buttons have been made thinner as well.

We'll probably want to find a different icon for the List block, or alternately a different way of showing the types of lists.

Update: We agreed to not include text alignment control for List block:

I'd like to echo the concerns of the others here and say that while this consistency is nice, I can't really imagine a real-world use case that works aesthetically. I suggest NOT including alignment controls on the List block.

See the full discussion in #16792