chat: allow tools to report progress

[connor4312]

This adds a toolProgress proposed API that allows extensions to report
progress keyed on the toolInvocationToken. Internally, when given to a
tool, this now includes the call ID of the tool.

We can use that both from extensions and internally to report progress
for tools, and I hooked this up for MCP servers. Currently only the text
is updated.

25-04-7d106ff6-a3f5-47f1-9c07-f428a166149c.1.mp4

Involved some changes in the progress service internally:

• Previously viewId was a naked string, I wrapped it in an object to
  make it more identifiable.
• The progress service is in workbench/services and directly calls
  into other services to effect progress. In leui of going for a full
  'contribution' model, I made a small ILanguageModelToolProgressService
  that it writes state into and that can be read back out. The state
  (an observable) is kept as long as progress is ongoing or this is
  is an observer.

Closes #244754
Closes #244751 (last adoption item)

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![IMG_0272

](https://github.com/user-attachments/assets/e6009c47-e8f7-4f8d-b2be-9a9c11d1cc1d)

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[connor4312]

Sounds good, will adjust 👍

[roblourens]

We should discuss in the API sync too. MCP servers can take advantage of this now? Would like to finalize it next month at least.

addressed

[abdhx]

👋 @connor4312
I use a tool that reports the progress via ctx.report_progress from the python mcp SDK.
But I cannot see the progress in vs code.
The progress is working fine in other mcp clients.

My server sent

notification/progress

{
    method: "notification/progress"
    params: {
        progress: 2
        total: 2
        message: "Hello world"
    }
}