Web Terminal with persistent disk

Description

Google and Microsoft have cloud shells that spin up docker images, but give you disk space (5GB) that is persisted between sessions. We should offer something like this.

Proposal

Links / references

• Google Cloud Shell
• Azure Cloud Console

Documentation blurb

(Write the start of the documentation of this feature here, include:

1. Why should someone use it; what's the underlying problem.
2. What is the solution.
3. How does someone use this

During implementation, this can then be copied and used as a starter for the documentation.)