KImageFormats v6.0.0 is now available (which should be Qt 6-compatible)

Readme: Clarify and fill in missing information for Nix(OS) install instructions

Fix LMDB link in the README since the previous one led to an error page

fixes #1718

Should fix 1707

(since it is fixed there)

Fix OpenGL video sinkchain crash

Use `XDG_ACTIVATION_TOKEN` from environment variables by default

fixes #1247

* Initial support for d3d11 qml video item

* Windows screenshare support, D3D11

* misc fixes

* further window visibility checks

* preview updates

* fix qml preview

* fix compositor

* add libnice plugin dep

* re-run formatter

* final formatter fix [skip ci]

* fix tumbleweed build

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Co-authored-by: Joseph Donofry <rubberduckie3554@gmail.com>