Callers use ISourceText instead of IRawText or IRawTextProvider.
Model service holds the ownership of IRawText, Creation options and resolved options for model

 - model creation options can now be specified at a later stage

Part of #16509

Fixes #15748

Fixes #15514

Part of #15718

Fixes #14132

Fixes #14063

Part of #14181

Due to issues #14151, #14149 & #14182

This reverts commit b23229f6.

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