Layout Blocks - Simplified naming

As a Studio app builder, I can provide a friendly name to my layout block

AC

• UI shows that the name will be prefixed by "project id-" so that I understand what I should look for in the toolbox later when I will need to d&d that block

• Name can be a mix of
  • Lowercase letters
  • Numbers
  • Dashes ( - )
    (some people can be tempted to add .html otherwise)

• When name can't be used for some reason, the reason is shown and prevents me from creating the block
  • Invalid name: Name contains invalid characters. The following are accepted: lowercase letters, numbers, dashes ( - )
  • Already used: This name already exists.

• When creating the block "project id-" is used as a prefix