This reverts commit 8c520318.

fixes #77922

fixes #67367

* attempt at serializing grid

* use before shutdown event

* init some layout state for grid

We seem to use the readonly property way of exposing these values more widely. Standardizing this a bit across the codebase

fixes #77226
fixes #67366

Also: let the theme service not change classes on document.body but the actual container of the workbench

more consistency