split signing setup into pre-release hook (#794)

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

.github/scripts/apple-signing/setup.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -eu
+
+IS_SNAPSHOT="$1"
+
+## grab utilities
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+. "$SCRIPT_DIR"/utils.sh
+
+main() {
+
+  case "$IS_SNAPSHOT" in
+
+    "1" |  "true" | "yes")
+      commentary "assuming development setup..."
+      . "$SCRIPT_DIR"/setup-dev.sh
+      ;;
+
+    "0" |  "false" | "no")
+      commentary "assuming production setup..."
+      . "$SCRIPT_DIR"/setup-prod.sh
+      ;;
+
+    *)
+      exit_with_error "could not determine if this was a production build (isSnapshot='$IS_SNAPSHOT')"
+      ;;
+  esac
+
+  # load up all signing material into a keychain (note: this should set the MAC_SIGNING_IDENTITY env var)
+  setup_signing
+
+  # write out identity to a file
+  echo -n "$MAC_SIGNING_IDENTITY" > "$SCRIPT_DIR/$SIGNING_IDENTITY_FILENAME"
+}
+
+set +u
+if [ -z "$SCRIPT" ]
+then
+    set -u
+    # log all output
+    mkdir -p "$SCRIPT_DIR/log"
+    /usr/bin/script "$SCRIPT_DIR/log/setup.txt" /bin/bash -c "$0 $*"
+    exit $?
+elif [ -n "$SKIP_SIGNING" ]; then
+    commentary "skipping signing setup..."
+else
+  set -u
+  main
+fi