Improve PR check workflow

[GCHQ-Developer-530]

Summary

Currently there's a mainly empty PR check workflow running prettier checks before a PR can be merged. This needs improving with other checks.

💬 Description

An example of what could be added:

• Add lint to static analysis tests
• Add audit to static analysis tests (this will need an audit command adding into the package.json first)
• Add a new job for jest tests
• Add a new job for Cypress tests

💰 Use value

We would know nothing has been broken immediately and not have to pull the code down locally to check.