Extend setup cmake ability (#3349)

Summary:
For executorch users, we see a common pattern that they have to:

```bash
bash install_requirements.sh --pybind xnnpack

cmake -S . -Bcmake-out ...

cmake --build ...
```

This is repeating cmake build twice, the first one is inside setup.py.

Here I'm adding a way to allow setup.py to install the libraries seperately, by passing `CMAKE_ARGS` and `CMAKE_BUILD_ARGS` into setup.py, through `install_requirements.sh`.

After this change, user can do:

```bash
export CMAKE_ARGS="-DCMAKE_INSTALL_PREFIX=<install dir> \
  -DEXECUTORCH_BUILD_OPTIMIZED=ON \
  ..."

export CMAKE_BUILD_ARGS="--target install"

bash install_requirements.sh --pybind xnnpack
```

Then we should be able to find `libxnnpack.a` `liboptimized_ops_lib.a` etc under install dir.

Pull Request resolved: #3349

Reviewed By: mikekgfb

Differential Revision: D56560786

Pulled By: larryliu0820

fbshipit-source-id: fb6cd230df2317067f07ae0f1e72d0596b7b454b

install_requirements.sh

@@ -27,7 +27,6 @@ fi
 
 # Parse options.
 EXECUTORCH_BUILD_PYBIND=OFF
-CMAKE_ARGS=""
 
 for arg in "$@"; do
   case $arg in
@@ -110,4 +109,5 @@ $PIP_EXECUTABLE install --extra-index-url "${TORCH_NIGHTLY_URL}" \
 
 EXECUTORCH_BUILD_PYBIND="${EXECUTORCH_BUILD_PYBIND}" \
     CMAKE_ARGS="${CMAKE_ARGS}" \
+    CMAKE_BUILD_ARGS="${CMAKE_BUILD_ARGS}" \
     $PIP_EXECUTABLE install . --no-build-isolation -v

setup.py

@@ -399,6 +399,14 @@ def run(self):
         if "CMAKE_ARGS" in os.environ:
             cmake_args += [item for item in os.environ["CMAKE_ARGS"].split(" ") if item]
 
+        # Allow adding extra build args through the environment. Used by some
+        # tests and demos to expand the set of targets included in the pip
+        # package.
+        if "CMAKE_BUILD_ARGS" in os.environ:
+            build_args += [
+                item for item in os.environ["CMAKE_BUILD_ARGS"].split(" ") if item
+            ]
+
         # Put the cmake cache under the temp directory, like
         # "pip-out/temp.<plat>/cmake-out".
         cmake_cache_dir = os.path.join(repo_root, self.build_temp, "cmake-out")