Remove non-libuv code from Node extension

binding.gyp

build.yaml

src/node/ext/call.cc

src/node/ext/channel.cc

src/node/ext/completion_queue.cc

src/node/ext/completion_queue_async_worker.h

src/node/ext/completion_queue_threadpool.cc

src/node/ext/node_grpc.cc

src/node/ext/server.cc

src/node/ext/server_generic.cc

src/node/ext/server_uv.cc

templates/binding.gyp.template

tools/run_tests/helper_scripts/build_node.sh

tools/run_tests/run_tests.py

tools/run_tests/run_tests_matrix.py