Use docker multistage build

[zhukovgreen]

This MR introduces some refactoring of the Dockerfile such as:

• multistage build, where the poetry is installed in a separate stage and then the binary to be copied to the development stage (without build deps)
• versions, and dependencies are moved to the top as env vars

Using this approach allows the image to reduce from 829MB -> 675MB

[playpauseandstop]

Hi @zhukovgreen

Nice idea! Merging your MR as is and will work next week to update images to latest Python and dev versions

Also, will change poetry-builder-base stage to poetry-stage