fix(install): Add -o flag to unzip to match tar (#3727)

By default, unzip will attempt to query the user when files to be
installed already exist. Unfortunately, if the install script is run
with `sh -s`, unzip will read the remaining portion of the script as
input, resulting in a mess on the terminal.

This commit changes the unzip behavior to clobber existing files: this
already happens for platforms using tar, so it's not hugely breaking
(and I could find no evidence that we believe this is more likely to
cause issues on Windows)

install/install.sh

@@ -116,7 +116,7 @@ unpack() {
       return 0
       ;;
     *.zip)
-      flags=$(test -z "${VERBOSE-}" && echo "-qq" || echo "")
+      flags=$(test -z "${VERBOSE-}" && echo "-qqo" || echo "-o")
       UNZIP="${flags}" ${sudo} unzip "${archive}" -d "${bin_dir}"
       return 0
       ;;