Choose tooling for Prometheus UI style guide / component library

[amy-super]

We need to choose a tool that will house the Prometheus UI style guide / component library. While Figma is currently the default choice for many users, it's not a comfortable tool for non-designers to use. Additionally, it's a proprietary tool with a lot of paid-only features.

This sub-issue will cover evaluating tools that may be a better fit for open source work with software engineers. Ideas include:

• Penpot @nwanduka
• Pencil @amy-super
• Affinity @vampirarte
• More to be added

Note that we should also evaluate Figma against the open source tools.

[amy-super]

@amy-super create a list of questions to be answered by all reviewers.