This commit adds a `NewEntryPointFileWriter` that will be used in
webpack integration. Instead of overwriting files in-place, this `FileWriter`
will make a copy of the TS program files and write the transformed files
there. It also updates the package.json with new properties that can be
used to access the new entry-point format.
FW-1121
PR Close#29092
By ensuring that EntryPointBundle contains everything that `Transformer.transform()`
needs to do its work, we can simplify its signature.
PR Close#29092
