Fixes #241090

* add first version of `AbstractChatEditingModifiedFileEntry`
* remove `IModifiedFileEntry#originalModel`
* reduce usage of `IModifiedFileEntry#diffInfo`

fyi @DonJayamanne notebook world needs cleanup here, it should not depend on modified file entries for text documents anymore

…#241118)

* tests - enable API tests with test runner

* windows

* use correct specific tests per api workspace type

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Co-authored-by: Connor Peet <[email protected]>

* added some issue reporter styling fix

* better fix

* some revets

- We now keep a 'postEdit' snapshot so we can make sure we're always
  able to show diffs, fixing the issue with the last pill and some
  other state bugs. I think this fixes microsoft/vscode-copilot#13229
- Made the observable for `getEntryDiffBetweenStops` proper and react to
  various updates. Made its type independent of the IDocumentDiff @jrieken
- Clicking on a pill now opens the change made at that point in time.

fix #239977

Make sure folders are requested when files are

If we have a part that isn't rendered, then we loop forever trying to render it and the response is never marked as complete, so the toolbar is hidden.

Revert "tests - enable API tests with test runner (#240876)"

This reverts commit 0c4d858.