Add basic multi-arch build support

[adamus1red]

This PR adds support for building the container as both AMD64 and ARM64. See #32

Base image supports linux/amd64, linux/arm/v7, and linux/arm64

Appears to work as expected when running on Raspberry Pi 4 running Alpine Linux 3.16

pi-4-1:~# uname -a
Linux pi-4-1 5.15.62-0-rpi4 #1-Alpine SMP PREEMPT Wed Aug 24 17:55:41 UTC 2022 aarch64 GNU/Linux
pi-4-1:~# docker logs -f 5f51b19f1a54

--------------------------------------------------------------------
 ____                             ____  _     _        _   _
/ ___|  ___ _ ____   _____ _ __  / ___|(_) __| | ___  | | | |_ __
\___ \ / _ \  __\ \ / / _ \  __| \___ \| |/ _` |/ _ \ | | | |  _ \
 ___) |  __/ |   \ V /  __/ |     ___) | | (_| |  __/ | |_| | |_) |
|____/ \___|_|    \_/ \___|_|    |____/|_|\__,_|\___|  \___/| .__/
                                                            |_|

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GID/UID
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User uid:    1000
User gid:    1000
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🔐 SSL_MODE has set to FULL, setting the web server to work in HTTPS only...
🏃‍♂️ Checking for Laravel automations...
🔐 Linking the storage...
🏃‍♂️ An SSL key was not detected, so I'll generate a self-signed SSL certificate pair for you...
........+..+...+....+........+......+.+.....+.............+.....+..........+...+...+..+...+.......+...+..+.........+.........+....+......+...........+.+..+......+......+.+.....+...+.+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*........+...+...+..+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*..........+...+............+.+......+......+.....+...+.+......+..+.............+...+...............+......+.....+.........................+...+...+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.....+..+...+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*..+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*.+.+...........+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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   INFO  The [public/storage] link has been connected to [storage/app/public].

🐇  Configuring Speedtest Tracker...
🙄  Database file not found, creating...
🔗  Creating database symlink
🙄  Environment file not found, creating...
🔗  Creating symlinks to config and log files
⏳  Generating app key...
[23-Oct-2022 01:00:50] NOTICE: fpm is running, pid 107
[23-Oct-2022 01:00:50] NOTICE: ready to handle connections
[23-Oct-2022 01:00:50] NOTICE: systemd monitor interval set to 10000ms
🔒  Fixing app path file permissions
💰  Building the cache...
127.0.0.1 - - [23/Oct/2022:01:00:51 +0000] "GET /ping HTTP/1.1" 301 162 "-" "curl/7.81.0"
🚛  Migrating the database...
✅  All set, starting Speedtest Tracker container...
⏰  Starting the cron service...
💪  Starting the queue worker...
10.0.10.218 - - [23/Oct/2022:01:00:56 +0000] "GET / HTTP/2.0" 302 378 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:106.0) Gecko/20100101 Firefox/106.0"

See https://github.com/adamus1red/speedtest-tracker-1/pkgs/container/speedtest-tracker-1/46905243?tag=adamus1red-multiarch for sample container image built from this PR with this action https://github.com/adamus1red/speedtest-tracker-1/actions/runs/3305287445

[alexjustesen]

On my radar for today, this will push me to get my rpi rack installed again

[alexjustesen]

Builds worked for my on rpi 4b's