[ECS agent] Snap Package Support (Feature Request)

I was thinking in the install and setup could be improved for Ubuntu and other Linux distros by having a [snap package](https://snapcraft.io/) version. If it's not a priority would you mind if I made the snap?

[Crafting your first snap](https://tutorials.ubuntu.com/tutorial/create-your-first-snap#0)

[Build and test snap](https://snapcraft.io/build)

[Getting Started snap template](https://github.com/snapcrafters/fork-and-rename-me)

The issue names no repository files, tests, or entry points. Start by reviewing the ECS agent's Ubuntu and Linux installation and setup path, then confirm the intended Snap package scope with maintainers; done means the agent can be installed and set up through a tested Snap package.

Written by the indexing model from the issue text.