feat: expand Calamares installer with DM chooser, explicit DE packages, and custom packages module

- Add packagechooser@dm instance for display manager selection (SDDM/LightDM/LXDM/LY)
- Expand desktop environment package lists (Xfce MATE LXQt i3) with explicit packages
- Change plasma -> plasma-meta and lsb-release -> antergos-lsb-release
- Add bootloader, displaymanager, grubcfg, postcfg, services-artix module configs
- Install antergos-release, antergos-wallpapers, antergos-grub-theme via basestrap
- Add custom packages/main.py with one-at-a-time install and --overwrite='*'
- Add --overwrite='*' to basestrap main.py for pacman -Sy operations

iso-profiles/antergos/live-overlay/etc/calamares/modules/grubcfg.conf

@@ -0,0 +1,20 @@
+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+---
+overwrite: false
+
+prefer_grub_d: false
+
+keep_distributor: false
+
+kernel_params: [ "quiet" ]
+
+defaults:
+    GRUB_TIMEOUT: 5
+    GRUB_DEFAULT: "saved"
+    GRUB_DISABLE_SUBMENU: true
+    GRUB_TERMINAL_OUTPUT: "console"
+    GRUB_DISABLE_RECOVERY: true
+    GRUB_THEME: "/usr/share/grub/themes/antergos/theme.txt"
+
+always_use_defaults: false