Better UI for creating/editing libraries

[ebruchez]

Following #6518/#5495.

The idea is that we want to make it more explicit how to handle libraries. In general, those will be few, typically a couple:

• global library (_)
• app library

Steps:

• split "New Form"/"New Library
• validate _/library
• could be a new tab in the Form Settings dialog?
  • but then would need ability to switch from form to library? or not?
• create new template for "Library" Or separate tab? Or checkbox?
• when editing, must set form name to library automatically
• allow importing Global Library from resources if the library does not exist in Form Builder or published (see New naming convention for global library #5495)
  • import UI
  • ship _ library in resources