Add configuration option to keep title editable

Hi can you tell me more details about it please?

Basically some websites may want to provide a default title, but still allow users to edit it. Like this:

Here is the proposed configuration form that allows site builder to opt into this feature.

If we really want to make this a robust feature, we could create a permission so that some users can edit this field and other can't.
And as discussed in this issue ✨ Add block type to description Needs work it would be nice to be make the default title configurable. But at a baseline I think we should provide the option.