Message Model - XSD generation restriction

Quick Start wizard for generating new message models from XSDs needs enhancing.

The quick start wizard has it's issues in IIB 9 and 10:
- It assumes you are starting from scratch i.e. establishing a new
Message Model, it doesn't support refactoring, regeneration of an
existing Message Model
- It doesn't support loading XSDs into a "folder" (something we have to
do because of the other contention issues that we've found working with
Message Models)

...but critically, it was the only import method that supported
hierarchical XSD imports, following XSD import statements to bring in
dependent XSDs, instead of simply dumping a single, flat XSD at the root of the Message Model.

Fast-forward to IIB v10 now...

We now find that the
Quick Start wizard FORCES you to create Message Models in a "shared"
library... It will not allow you to generate a Message Model from an
XSD into a "static" library.

Other import / message model generation techniques allow you to select
between a shared or a static library, but they don't support
hierarchical XSDs or follow XSD import statements to bring in dependent
XSD files.

There seems to be no reason to these restrictions /
inconsistencies...

In summary - "one of" our less than ideal workarounds for using Message
Models (as opposed to Message Sets - which worked perfectly) in IIB v9,
has now been restricted in IIB v10 such that we need to apply some kind
of workaround on top of the existing workarounds,