add ttmetal-to-cpp translation for manual/lit testing

[vroubtsovTT]

It would be convenient to have a quick way to examine codegen'ed c++ on cmd line and possibly match actual c++ text in lit CHECK tests.

We already have ttmetal-to-flatbuffer which outputs binary fb blobs with kernels serialized inside as strings, but that's suboptimal. We now also have ttkernel-to-cpp-noc and ttkernel-to-cpp-tensix. ttmetal-to-cpp would be similar to the former but output all c++ kernels to stdout, possibly taking a parameter to select only one ttkernel::ThreadType.