Road to v8.0.0

[JammingBen]

This issue has the purpose to keep track of tasks that need to be handled before finally releasing the next major version v8.0.0.

• Update dependencies
• Add missing changelog items for breaking changes:
  • Search term is being wrapped in *...* for a wildcard search
  • WebDAV implementation moved to web-client -> changed dav propteries
  • Extension framework (?)
• Fix web-pkg and web-client releases
• Add missing dev-documentation
  • Extension system (see Dev docs for extension framework #9892)
  • OCM app (needs to be productized first)
• Check and remove deprecations -> Remove deprecated code after prior notices #9959