Implement Frontend javascript Testing

[sbland]

Which user story or feature is this technical work related to?
General UI including dataviz amends

Describe the aspect of the user stories or features that this technical work is part of
Implement automated testing for the javascript components including the dataviz

Additional context
Options:

• Jest - A bit outdated now
• Vitest - I've only set this up with PNPM rather than NPM so need to check if this causes any issues
• Storybook - I've not used this before but keep meaning to try it out. Relies on Vitest https://storybook.js.org/docs/writing-tests

[sbland]

I've implemented Vitest here: #533