Byte code dump tasks

[TheMostDiligent]

• Move BytecodeDumper to anonymous namespace
• If dump directory does not exist, none of the other directories will be created and dump will fail. The packager must create it.
• Rework BytecodeDumper::WorkingDirectory to use std::stack. This will make it more robust. It is totally OK to traverse the entire stack every time in ComputePathFor. Compared to file operations this is will be done in no time
• Add tests for byte code dump: create temporary directory in the current working directory (assets), dump files for each backend there and verify that files exist. Delete the directory afterwards.
  • If Metal is supported, validate that .metal and .metallib files are also created
• Verify that everything works when either path or shader name contains white spaces, add tests