BUGFIX: Parse EEL Expressions in "type"

[mhsdesign]

Currently the field type does not allow eel expressions:

childNodes:
  product-details:
    type: "${data.isSpecial ? 'My.Site:NodeType' : 'My.Site:NodeType.Special'}"
    properties:
       foo: bar

It might seem to be an odd usecase, as the property overlap of two different nodeTypes might not be that high. Nevertheless i have a usecase for it and want it, and dont think we necessarily need to restrict it to simple strings only.