Revamp Web UI

[VaderZ]

There multiple issues that have to be addressed in Web UI:

• upgrade to the latest version of Vuestic UI
• remove leftovers of Vuestic Admin template
• use generated OpenAPI client instead of raw axios, group everything under services namespace to follow VueJS conventions
• clearly separate components from pages/views, use smaller components (e.g. test view component have to be broken down into separate parts)
• use global events for refreshes instead of local timers in every component
• state storage usage is quite messy, see if this can be cleaned up
• integrate authentication (requires at least user management page)