Create a scheduled CI job to scan EUI docs

[1Copenut]

Description

Create a new CI job to scan EUI docs for a11y violations. This task should run nightly and not disrupt our regular PR jobs.

[github-actions[bot]]

👋 Hi there - this issue hasn't had any activity in 6 months. If the EUI team has not explicitly expressed that this is something on our roadmap, it's unlikely that we'll pick this issue up. We would sincerely appreciate a PR/community contribution if this is something that matters to you! If not, and there is no further activity on this issue for another 6 months (i.e. it's stale for over a year), the issue will be auto-closed.

[JasonStoltz]

Dependent on new docs platform being launched