Add more defaults to format definitions

[thibaudcolas]

Feature. There should be more defaults for "built-in" formats for which a type constant is defined. description, label or icon should be pre-defined. Potentially, entities could have a default decorator.

What is the current behavior?

No defaults are provided - a toolbar button can contain no content at all, and every editor has to define all of the above.

What is the expected behavior?

Be able to get an editor set up by just providing type values and nothing else.