Pull in protoc-gen-grpc-java for windows

Summary:
This D70602802 caused some failures on windows.
Fixing here by providing executable for windows.

allow-large-files

```
arc artificer download \
    io.grpc:protoc-gen-grpc-java:1.10.1:linux-x86_64 \
    io.grpc:protoc-gen-grpc-java:1.10.1:osx-x86_64 \
    io.grpc:protoc-gen-grpc-java:1.10.1:windows-x86_64

chmod a+x \
    third-party/java/io/grpc/protoc-gen-grpc-java/1.10.1/protoc-gen-grpc-java-1.10.1-linux-x86_64.exe \
    third-party/java/io/grpc/protoc-gen-grpc-java/1.10.1/protoc-gen-grpc-java-1.10.1-osx-x86_64.exe \
    third-party/java/io/grpc/protoc-gen-grpc-java/1.10.1/protoc-gen-grpc-java-1.10.1-windows-x86_64.exe
```

Reviewed By: navidqar

Differential Revision: D70734277

fbshipit-source-id: 90bd5e45d0e3879639960cdb4674bc3065f0a31f

prelude/toolchains/android/tools/protobuf/BUCK

@@ -22,5 +22,6 @@ fb_native.command_alias(
     platform_exe = {
         "linux": "fbsource//third-party/java/io/grpc/protoc-gen-grpc-java:protoc-gen-grpc-java-linux-x86_64",
         "macos": "fbsource//third-party/java/io/grpc/protoc-gen-grpc-java:protoc-gen-grpc-java-osx-x86_64",
+        "windows": "fbsource//third-party/java/io/grpc/protoc-gen-grpc-java:protoc-gen-grpc-java-windows-x86_64",
     },
 )