Configure destination of grub.cfg at overlay render time

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

overlays/host/rootfs/grub.cfg.ww

@@ -0,0 +1,30 @@
+{{ file (print .Tftp.TftpRoot "/warewulf/grub.cfg") }}
+# This file is autogenerated by warewulf
+# Host:   {{ .BuildHost }}
+# Time:   {{ .BuildTime }}
+# Source: {{ .BuildSource }}
+echo "================================================================================"
+echo "Warewulf v4 now iXPE booting with grub"
+echo "================================================================================"
+smbios --type 3 --get-string 8 --set assetkey
+set timeout=2
+# Must chainload in order to get kernel args for specific node
+menuentry "Load specific configfile" {
+    conf="(http,{{.Ipaddr}}:{{.Warewulf.Port}})/efiboot/grub.cfg?assetkey=${assetkey}"
+    configfile $conf
+}
+menuentry "Chainload shim from image" {
+    shim="(http,{{.Ipaddr}}:{{.Warewulf.Port}})/efiboot/shim.efi?assetkey=${assetkey}"
+    chainloader ${shim}
+}
+menuentry "UEFI Firmware Settings" --id "uefi-firmware" {
+    fwsetup
+}
+menuentry "System restart" {
+    echo "System rebooting..."
+    reboot
+}
+menuentry "System shutdown" {
+    echo "System shutting down..."
+    halt
+}