edm.xml: types TSimpleIdentifier, TNamespaceName, and TQualifiedName too restrictive

The simple types TSimpleIdentifier, TNamespaceName, and TQualifiedName are currently based on xs:NCName which adds restricitions beyond what CSDL defines.

Base these simple types on xs:string instead, with minLength="1".

Also check other simple types that are currently based on xs:token whether they should better also be based on xs:string, and maybe just to be consistent.