Create Layer renditions.

In the first iteration PNG renditions shall be created.

1. Avoid renditions for following types.
   1. Skipped
   2. Merged
   3. Text
   4. Symbol instance
   5. Root
   6. Stray
2. Use uuid as the name of the file
3. Dump the renditions in a temp folder, XD won't let you create custom paths.
4. Figure out how to do compositing.