Require aliases for schemas and require alias-qualified names

To simplify lookup of qualified names the CSDL JSON representation initially required namespace-qualified names. This got some pushback as namespaces are typically long to be unique and alias-qualified names are more readable, so aliases were re-introduced.

Why not require aliases and alias-qualified names in CSDL JSON documents to further increase readability by avoiding the arbitrary mix of namespace- and alias-qualified names.