Create an arm64 version for Linux

[calejvaldez]

Problem Description

Linux on ARM is starting to gain some kind of traction, but Zulip doesn't include an arm64 version. I understand we could just build this ourselves with the open-source code, but I think it should also be added on the Zulip downloads page for Linux.

Proposed Solution

Add a build of Zulip for Linux arm64 on the Downloads page.

Describe alternatives you've considered

I downloaded the source code from GitHub and created an arm64 tar.gz file. This works fine.

Additional context

Screenshot of an attempted install using snap: