This step converts each file into an exported module by hoisting the namespace bodies into the global scope and transferring internal markers down onto declarations as needed.
The namespaces are reconstructed as "barrel"-style modules, which are identical to the old namespace objects in structure. These reconstructed namespaces are then imported in the newly module-ified files, making existing expressions like "ts." valid.
* Move most harness globals into namespaces
* Remove forward declaration from `createMapShim` and move all `Map` declarations into one file
* A small pile of more changes to get the harness transforming
