Use custom Yarn cache directory

Makes it easier to upload and restore.

scripts/cacher.sh

@@ -23,7 +23,7 @@ restore() {
 # the cache-upload directory will be uploaded as-is to the code-server bucket.
 package() {
 	mkdir -p "cache-upload/cache/$1"
-	tar czfv "cache-upload/cache/$1/$tar.tar.gz" node_modules source /usr/local/share/.cache/yarn
+	tar czfv "cache-upload/cache/$1/$tar.tar.gz" node_modules source yarn-cache
 }
 
 main() {

scripts/ci.bash

@@ -21,6 +21,9 @@ function main() {
 		mv "vscode-$vscode_version-source" "source/vscode-$vscode_version-source"
 	fi
 
+	YARN_CACHE_FOLDER="$(pwd)/yarn-cache"
+	export YARN_CACHE_FOLDER
+
 	# Always minify and package on tags since that's when releases are pushed.
 	if [[ -n ${DRONE_TAG:-} || -n ${TRAVIS_TAG:-} ]] ; then
 		export MINIFY="true"