Allow systemd-gpt-auto-generator to mount the ESP automatically

See merge request !195

grub-mkconfig from grub 2:2.06.r566.g857af0e17-1 sets up loading a `bli`
module that sets `LoaderDevicePartUUID`. This means that
systemd-gpt-auto-generator can now automount partitions when GRUB is
used as the boot loader.

See https://wiki.archlinux.org/title/systemd#GPT_partition_automounting

Revert "Create /etc/resolv.conf as a relative symlink"

See merge request !196

Something about the relative symlink makes arch-chroot go haywire
when invoked by `build.sh` and create crazy bind mounts like
/tmp/boxes-tmp/tmp.cwtHQPvydE/mount/tmp/boxes-tmp/tmp.cwtHQPvydE/mount/run/systemd/resolve/stub-resolv.conf

Revert to an absolute symlink until the issue is fixed.
See https://github.com/archlinux/arch-install-scripts/issues/55

This reverts commit ff22bfc4.

The docker runners are preferred as they are faster and use fewer
resources.

[1] https://github.com/hashicorp/vagrant/commit/b40f6e5fdae1113518e9c92f96dfcd364b646ff9

Create /etc/resolv.conf as a relative symlink

See merge request !194

This matches with /usr/lib/tmpfiles.d/systemd-resolve.conf.

Initialize an empty pacman keyring in the target

See merge request !193

Use `pacstrap -K` to create a new pacman keyring instead of copying it
from the host. While it gets removed either way in `image_cleanup`, it
seems better to avoid using things from the host.

TRIM the EFI system partition

See merge request !192

Linux supports TRIM on VFAT, so run fstrim against the ESP mountpoint.

Credit to @nl6720.

Clarify release schedule

See merge request !191

"Biweekly" is ambiguous as it could mean either "once every two weeks"
or "twice a week".
Use the word "fortnightly" to remove the ambiguity.

Enable DHCPv6 client

See merge request archlinux/arch-boxes!190

Set `DHCP=yes` in `/etc/systemd/network/80-dhcp.network` to start both
DHCPv4 and DHCPv6 clients. This provides IPv6 for networks using DHCPv6
without RA.

It should not have much effect of networks with working RA since the
`IPv6AcceptRA` option is enabled by default for these connections anyway.

Create the swap file with the btrfs utility

See merge request archlinux/arch-boxes!189

Use `btrfs filesystem mkswapfile` instead of performing all the actions
manually.

The community repository has been merged into extra as part of the git
migration.

[1] https://archlinux.org/news/git-migration-announcement/

Add UEFI support

Closes #141

See merge request archlinux/arch-boxes!182

Test basic and cloudimg image booting on x64 UEFI using qemu with edk2-ovmf.

This makes it clear that they only test booting in BIOS mode.

Create a 300 MiB EFI system partition.
Install GRUB to the default/fallback boot path on the ESP. This way it will boot everywhere and NVRAM will not be touched.

* dosfstools is needed for fsck.vfat,
* efibootmgr is for manipulating UEFI boot entries. This is not done by any of scripts since we don't want to touch NVRAM.

Implements #141

build.sh executes mkfs.btrfs. Currently it only works because the environment
where build.sh runs (an arch-boxes image itself) already has btrfs-progs.

feat: Remove build-host.sh as it is no longer used

See merge request archlinux/arch-boxes!188

Rename the script to just `build.sh` to use a more generic name and
description.

The use of `build-host.sh` has been removed in
3bda5b26.
In the case a script is needed to run `build-inside-vm.sh` in such an
environment again, it is advised to rely on
https://gitlab.archlinux.org/archlinux/ci-scripts/ instead.

Use DHCP for all ethernet interfaces

See merge request archlinux/arch-boxes!186

Change the interface match of systemd-networkd from `eth0` to `eth*` to
match all local ethernet interfaces.
This is particularly useful for Vagrant, as it requires two interfaces
(one solely used for managing the machine, another e.g. for outbound
connections) and for machines in general, as depending on their context
(e.g. plain libvirt) the user may attach more interfaces and having DHCP
available for them out-of-the-box is a quality of life improvement (as
we do not know what the user intends to do with eth0 by default).

Align the partition end sectors and add partition names

See merge request archlinux/arch-boxes!179

A swap file cannot be referenced by its UUID so there's no need for it to have one in the first place.

sgdisk by default only aligns the partition start. Use the --align-end option to align the partition end too.

Additionally:

* Add PARTLABEL values to all partitions.
* Do not hardcode the partition number and end sectors in sgdisk commands by using the special value "0".
* Follow the Discoverable Partitions Specification by using the "Linux x86-64 root" partition type.

Switch to Geo IP mirrors

See merge request archlinux/arch-boxes!184

Reflector can take a long time to figure out the best mirrors and blocks
ssh access which makes some automation slow (Waiting longer then 1
minute on a functioning server). This approach is similiar to what we
have for our docker images.

Enable systemd-time-wait-sync.service and order pacman-init.service after time-sync.target

See merge request archlinux/arch-boxes!183

If the hardware clock is not in UTC, but instead UTC+X, the pacman keyring may end up with keys created in the future.
Ensure the time is synced before starting pacman-init.service.

This fixes the equivalent of archiso's archlinux/archiso#190 for arch-boxes.

Order pacman-init.service before archlinux-keyring-wkd-sync.service

See merge request archlinux/arch-boxes!180

archlinux-keyring-wkd-sync.service needs an initialized pacman keyring to work.