DEVTOOLS-7936: Set permissions on public packages

This updates the public repository upload process to change the group on
the uploaded files to `cf` and adds the write permission for members of
the group. This should allow the `cf` user to properly overwrite the
file when signing it.

Author: tvarney

Makefile

@@ -89,6 +89,7 @@ define publish_package
 	for HOST in $(CF_PKG_HOSTS); do \
 		ssh-keyscan -t rsa $$HOST >> ~/.ssh/known_hosts; \
 		scp -4 cloudflared*.$(1) cfsync@$$HOST:/state/cf-pkg/staging/$(2)/$(TARGET_PUBLIC_REPO)/cloudflared/; \
+		ssh cfsync@$$HOST 'chgrp cf /state/cf-pkg/staging/$(2)/$(TARGET_PUBLIC_REPO)/cloudflared/*.$(1) && chmod g+w /state/cf-pkg/staging/$(2)/$(TARGET_PUBLIC_REPO)/cloudflared/*.$(1)'; \
 	done
 endef
 
@@ -225,4 +226,4 @@ vet:
 
 .PHONY: msi
 msi: cloudflared
-	go-msi make --msi cloudflared.msi --version $(MSI_VERSION)
+	go-msi make --msi cloudflared.msi --version $(MSI_VERSION)