Deploy mac OS solana-install update package to testnets (#4595)

scripts/solana-install-update-manifest-keypair.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+#
+# Convenience script to easily deploy a software update to a testnet
+#
+# Prerequisites:
+# 1) The default keypair should have some lamports (eg, `solana-wallet airdrop 123`)
+# 2) The file update_manifest_keypair.json should exist if this script is not
+#    run from the CI environment
+#
+set -e
+
+OS=${1:-linux}
+
+case "$OS" in
+osx)
+  TARGET=x86_64-apple-darwin
+  ;;
+linux)
+  TARGET=x86_64-unknown-linux-gnu
+  ;;
+windows)
+  TARGET=x86_64-pc-windows-msvc
+  ;;
+*)
+  TARGET=unknown-unknown-unknown
+  ;;
+esac
+
+SOLANA_INSTALL_UPDATE_MANIFEST_KEYPAIR="SOLANA_INSTALL_UPDATE_MANIFEST_KEYPAIR_${TARGET//-/_}"
+
+# shellcheck disable=2154 # is referenced but not assigned
+if [[ -z ${!SOLANA_INSTALL_UPDATE_MANIFEST_KEYPAIR} ]]; then
+  echo "$SOLANA_INSTALL_UPDATE_MANIFEST_KEYPAIR not defined"
+  exit 1
+fi
+
+echo "${!SOLANA_INSTALL_UPDATE_MANIFEST_KEYPAIR}" > update_manifest_keypair.json
+ls -l update_manifest_keypair.json