Issues with reusable block titles

Problem/Motivation

When creating a new 'reusable block', the block title defaults to the block types readable name (e.g. "basic block"), not the title provided in the create block form.

Additionally, when you re-use a reusable block, the 'title' field defaults to the 'admin title' (block description), not the title of the block that was used when you originally created the block.

Also, not sure if this was intended, but the title of the block is not universal, while the body is. This may be intended, but the info block that shows up (yellow box at the top of the form) implies that anything you change on this form update globally. (When in fact the title is not global, only the body is).

Steps to reproduce

• Create a 'new' re-usable block (not an existing one)
• Set the admin title to something
• Set the 'title' in the form field to something, and enable 'display title'
• The block is added to the page with the title 'Basic block' (or whatever the human readable name of the block type is)
• Add the block to the page again by selecting it from the content blocks list. The 'default value' for the title field is set to the 'block description' (admin title)

Proposed resolution

The default title for newly created blocks should be what you provide in the 'Title' field on the create block form.
When adding a new instance of a previously created block, the default 'Title' field should default to the title of the original block (or no value at all).