Make type import/export API Annotation friendly

At the moment an export of the form

   type C(..)

is parsed by the rule

  |  'type' oqtycon           {% amms (mkTypeImpExp (sLL $1 $> (unLoc $2)))
                                     [mj AnnType $1,mj AnnVal $2] }

This means that the origiinal oqtycon loses its location which is then retained in the AnnVal annotation.

The problem is if the oqtycon has its own annotations, these get lost.

e.g. in

  type (?)(..)

the parens annotations for (?) get lost.

This can be solved by introducing a new IE constructor IEVarType, treated exactly the same as IEVar in the rest of the processing.

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