Add macOS and Linux jpackage native installer build script

Author: mearvk

installer/build-native.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+set -eu
+ROOT=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+cd "$ROOT"
+
+mvn -B clean package
+mkdir -p dist
+APP_VERSION=$(mvn -q -DforceStdout help:evaluate -Dexpression=project.version)
+JAR="target/us-house-installer-${APP_VERSION}.jar"
+
+if [ ! -f "$JAR" ]; then
+  echo "Build did not produce $JAR" >&2
+  exit 1
+fi
+
+case "$(uname -s)" in
+  Darwin)
+    jpackage --type dmg --name US-House-Installer --input target --main-jar "$(basename "$JAR")" --main-class us.house.installer.USHouseInstaller --dest dist
+    ;;
+  Linux)
+    jpackage --type deb --name us-house-installer --input target --main-jar "$(basename "$JAR")" --main-class us.house.installer.USHouseInstaller --dest dist
+    ;;
+  *)
+    echo "Use build-native.ps1 on Windows." >&2
+    exit 2
+    ;;
+esac
+
+echo "Native installer written to $ROOT/dist"