[Security] Run Cloudbeaver as non-root by default (to be less vulnerable)

**Is your feature request related to a problem? Please describe.**
It would be a good point to **run Cloudbeaver with a non-root user to follow best security practises**
Reference of why this is important: https://docs.bitnami.com/tutorials/why-non-root-containers-are-important-for-security

**Describe the solution you'd like**
To do that, it should define a USER in the [Dockerfile](https://github.com/dbeaver/cloudbeaver/blob/devel/deploy/docker/Dockerfile)

I see that s[omeone mentioned already this](https://github.com/dbeaver/cloudbeaver/issues/349) and suggested a solution, but it was not added to the repo as default