[vscode][chore] Update theia.d.ts comments according to latest updates

[rschnekenbu]

As vscode.d.ts file evolves in comments, it would be nice to have similar evolutions in our comments, to ease the comparison of the theia.d.ts file compared to vscode.d.ts one. Goal of this task is to update comments on theia.d.ts file. No changes should be made to interfaces with this task