Add target to create a local PKGBUILD to install .deb on Arch

pacman target is somewhat broken, so let's do it similarly like the
official AUR package for local installs.

local-pkgbuild-template/PKGBUILD

@@ -0,0 +1,25 @@
+# Maintainer: su-ex <codeworks@supercable.onl>
+# Maintainer: SpiritCroc <aur@spiritcroc.de>
+# Contributor: David Mehren <david.mehren@udo.edu>
+
+pkgname=---appName----git
+_pkgver=---version---
+pkgver=${_pkgver//-/.}
+pkgrel=1
+pkgdesc="SchildiChat is a Matrix client based on Element with a more traditional instant messaging experience."
+arch=('x86_64')
+url="https://schildi.chat"
+license=('Apache')
+depends=('sqlcipher')
+provides=('---appName---')
+conflicts=('---appName---')
+source=("---debName---"
+        "---appName---.sh")
+sha256sums=('SKIP'
+            'SKIP')
+
+package() {
+  msg2 "Extracting the data.tar.xz..."
+  bsdtar -xf data.tar.xz -C "$pkgdir/"
+  install -Dm755 "${srcdir}"/---appName---.sh "${pkgdir}"/usr/bin/---appName---
+}

local-pkgbuild-template/schildichat-desktop.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+exec "/opt/---productName---/---appName---" "$@"