BUG: Record type-annotations sneak through records-to-tuples

[rrnewton]

This cropped up in mergeMonotonic (reuters test 7) after our new FIFO implementation was in place.

A reproducer was checked in here:
https://github.com/rrnewton/WaveScript/blob/0d3957aa588bc1fc216475b50b2c4e096b97153e/src/demos/wavescope/issue11_bug.ws

[rrnewton]

The problem in this case was a typical compiler bug, when desugaring record types, forgot to recursively desugar the types of each component, and hence a record-in-a-record would trigger this bug. It survived for a long time though.