Find a new way to validate icon props

We currently validate the icons during development mode against the existing list of icons: https://gitlab.com/gitlab-org/gitlab-ui/-/blob/920d1041bd2b8cbbcba7378ed5062e4b4f311790/src/components/base/icon/icon.vue#L11-23

The problem, the require is not really available and breaks in tools like Vite/Rollup per default.