* Test with Podman in CI
* Correct logic to copy Docker image to Podman
* Load necessary kernel modules in CI
---------
Co-authored-by: Jordan Potter <me@jordanpotter.com>
This dramatically reduces the size of the container from hundreds of MiBs to just over ten.
BEFORE
```
$ docker history ea2d6da4cbdc
IMAGE CREATED CREATED BY SIZE COMMENT
ea2d6da4cbdc 27 seconds ago /bin/sh -c #(nop) ENTRYPOINT ["/entrypoint.… 0B
2c7e3f0de3c8 27 seconds ago /bin/sh -c #(nop) COPY file:ad76fe44d1402628… 1.44kB
1a29ca960363 29 seconds ago /bin/sh -c apt-get update && apt-get install… 367MB
f643c72bc252 12 days ago /bin/sh -c #(nop) CMD ["/bin/bash"] 0B
<missing> 12 days ago /bin/sh -c mkdir -p /run/systemd && echo 'do… 7B
<missing> 12 days ago /bin/sh -c [ -z "$(apt-get indextargets)" ] 0B
<missing> 12 days ago /bin/sh -c set -xe && echo '#!/bin/sh' > /… 811B
<missing> 12 days ago /bin/sh -c #(nop) ADD file:4f15c4475fbafb3fe… 72.9MB
```
AFTER
```
$ docker history 6b71b07e8ccd
IMAGE CREATED CREATED BY SIZE COMMENT
6b71b07e8ccd About a minute ago /bin/sh -c #(nop) ENTRYPOINT ["/entrypoint.… 0B
898dbb77c8ce About a minute ago /bin/sh -c #(nop) COPY file:ad76fe44d1402628… 1.44kB
8470d1ebb9cb About a minute ago /bin/sh -c apk add --no-cache openreso… 7.37MB
d6e46aa2470d 6 weeks ago /bin/sh -c #(nop) CMD ["/bin/sh"] 0B
<missing> 6 weeks ago /bin/sh -c #(nop) ADD file:f17f65714f703db90… 5.57MB
```
To remove the need for running privileged mode, set the necessary
`net.ipv4.conf.all.src_valid_mark=1` sysctl via docker and modify the
`/usr/bin/wg-quick` script from setting the sysctl
* Set `net.ipv4.conf.all.src_valid_mark=1` sysctl via docker `--sysctl`
* Set CAPs of NET_ADMIN and SYS_MODULE instead of using `--privileged`
* Check that `net.ipv4.conf.all.src_valid_mark=1` is set in entrypoint
script
Fixes#2
