Add experimental desktop/ folder (#12374)

See README.md

Author: larryliu0820

desktop/README.md

@@ -0,0 +1,18 @@
+# Experimental: PyTorch Unified Python-less Solution
+
+This folder contains the experimental PyTorch Unified Python-less Solution, for both compiler and runtime. Proceed with caution.
+
+
+## torch dependency
+We use the pinned pytorch version from `install_requirements.py` and CI should be using `.ci/docker/ci_commit_pins/pytorch.txt` which should be consistent with `install_requirements.py`.
+
+
+## Compiler
+All code should live in `compiler/` folder. Code uses `torch` nightly as mentioned in torch dependency section.
+
+## Runtime
+All code should live in `runtime/` folder. CMake build system should leverage `libtorch` in the pip install of `torch` nightly. To build runtime, we need to point `CMAKE_PREFIX_PATH` to the pip install location of `torch` nightly. This way we can do:
+
+```cmake
+find_package(torch REQUIRED)
+```