feat(docker): add rustic to compiled docker image

[yeenbean]

Closes #13

[fangmarks]

@ChecksumDev @naterfute :3

[naterfute]

This would require building rustic every time, which is.... very inefficient. They offer pre-built binaries which I would like to opt for. I'm currently working on them.

[naterfute]

I added code to auto install it from the pre-built binaries from rustic themselves f131de3

[yeenbean]

@naterfute binstall pulls binaries by default and falls back to building if they don't exist. I suppose I should have explained that in my PR...

[naterfute]

I... Did not know that.

[yeenbean]

All good, I'll take the fault for that for not communicating it. :P Your solution works just as well. They have binaries for the couple platforms that we'd need to support.

[naterfute]

Which one do you think will be better, the url or the binstall? You obviously have more experience with this than I do? they will be basically the same yeah? your is just cleaner. So we can just merge that one in.

[yeenbean]

Let's either hold off on merging or merge yours in for now.

After I submitted the PR, I noticed mine does not grab arm builds with binstall, and I'd like to see if I can get that sorted so image builds don't take forever.

If you merge yours, I'll rebase and work from that version of the Dockerfile.

[naterfute]

Cool, alright. Mine is already on the main branch, so just go at it and reopen this if you figure out it(or open a new one)