TS 2.3.1 introduced a breaking change by [switching to covariant types for callbacks](https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#covariance-in-callback-parameters). This change tries to fix these compiler errors in the workbench codebase

Fixes #24409

**Bug**
Can't view cat gifs in VSCode resource viewer. We only display images that are < 1mb :(

**Fix**
Add a more specific error message for large images and adds button to try opening the file in an external program

- 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