EnvironmentService's config may be stale.

Part of #13733

Fixes #15515

Fixes #15260

Since text files in workspaces are now restored using the regular workspace
restore code and models check when opened if there is a backup available,
the registration and deregistration of workspace resources is no longer
necessary.

Fixes #14064

workspaces.json now tracks all workspaces
workspace.json now tracks a list of textfiles in the workspace

Part of #14064

Due to issues #14151, #14149 & #14182

This reverts commit b23229f6.

This reverts commit aab05a86.

This change does the following:
- filesToRestore are no longer checked at all, instead the the already existing
  editorStacks.model value from local storage restores the files just like
  normal.
- Loading of the resource is now solely the responsibility of
  TextFileEditorModel, removing a lot of the stuff being passed down through
  the layers.

Fixes #14100
Fixes #14067

Fixes #14068

Also clean up shutdown logic to fix issue where backup workspaces were not
being evicted from workspaces.json.