Add docker playground to practice tutorials

[sagarlakshmipathy]

Important Read

https://github.com/onetable-io/onetable/issues/257

What is the purpose of the pull request

Adds docker playground with spark and copies the bundled jar. This improvement lets the users to run the how-to tutorial,

Brief change log

Adds docker playground and copies the onetable bundled jar.

Verify this pull request

Ran local tests for docker. onetable-issue-257-tests.pdf

Ran npm start and visually tested the docs.