* fix spelling of 'iff' and 'idenifier'

* Keep 'iff' in comment if it means *if and only if*

Fixes #24409

- Wraps processed information from file
- Helper methods in TextModel to create RawText

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

Fixes #16491

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