Remove clinet argument.

Since clients communicate using only JSON there is no need for the
argument which was only used to select serialization format.
Remove 'SrcSpanInfo' string when serializing node.
Remove redudancy and test code.
Context menu support for hlint eta reduction.

These are only one line changes and will build slowly.
Make lambdaArgs query return full arguments and not just names.
Cosmetic code cleanup.