Includes CMake files and placeholder header, library, test tool, regression
test and unit test.
The aim for this project is to create a replacement for the existing ORC
Runtime that currently resides in `llvm-project/compiler-rt/lib/orc`. The new
project will provide a superset of the original features, and the old runtime
will be removed once the new runtime is sufficiently developed.
See discussion at
https://discourse.llvm.org/t/rfc-move-orc-executor-support-into-top-level-project/81049
