Migrate documentation frameworkt o Docusaurus 2

[mariusoe]

The current documentation is based on Docusaurus. Meanwhile, there is Docusaurus 2, providing new features, bugs and security fixes. The currently used Docusaurus should be migrated to Docusaurus 2. See also: https://v2.docusaurus.io/docs/migration

[aaronweissler]

Was put on hold after it turned out to not be trivial and due to discussions of replacing it anyways. There is a version in the branch https://github.com/aaronweissler/inspectit-ocelot/tree/feat/docusaurus-v2 created by following the migration guide using automated migration and then some additional manual changes, but despite looking correct it only shows the footer and header, and no correct colors on startup. I think it might be best to either start the migration anew, or even build the page anew in general based on the existing files using v2.