test(compartment-mapper): Add failing test for 1:* exports

[kriskowal]

Per #716 (comment), bundles do not yet support exporting a local variable by multiple names on the module exports namespace.

This will require a somewhat bold but manageable change to the structure of the bundle. I believe we can actually flatten the array of cells, giving every local variable of every module in the working set a unique index, then reusing the same cell for multiple properties of the module namespace object.

This will require more book-keeping up front, building out an index of the cells, but should actually have a nice effect on bundle size since the cells declaration can look more like:

const cells = new Array(length).fill().map(cell);

It will probably not be practical any longer to name the cells, since the names are not intrinsic to the cell, at a minor cost to the debug experience.