Update Dockerfile to use distroless base image

[niccoloraspa]

Addresses #816

Description

This PR introduces a new Dockerfile to build and distribute the osmosisd binary.
The Dockerfile uses multistage build process and serves osmosisd inside a distroless base container image.

To test the Dockerfile against the latest tag (but any commit will do):

git clone https://github.com/osmosis-labs/osmosis
cd osmosis
git checkout v6.3.0
# Replace Dockerfile with the one above
docker build -t osmosis:v6.3.0 .

Then you can run the container as you normally would do with the binary:

docker run osmosis:v6.3.0 version 
# 6.3.0

---

For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

[ValarDragon]

LGTM!

[czarcas7ic]

We should link at some point to document interacting with osmosisd via docker (i.e best way to automate getting required files for the home dir, basic docker commands, etc). This is great though, much needed!

[daniel-farina]

I had the same though as @czarcas7ic . I created an issue to track this:
osmosis-labs/docs#21

Everything else looks good, ready to merge @ValarDragon