Use work done progress to handle restore server side (#81233)

Followup to the canonical misc changes.  This PR has two parts

## Move server initiated restore entirely to server
Previously restores initiated by the server had to call out to the
client to setup the correct UI, which then called back to the server to
run the restore, all using custom LSP requests. This wasn't ideal as it
meant extra custom client side code and an extra server -> client ->
server loop.

Instead, we can utilize the standard LSP [server initiated work done
progress](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#serverInitiatedProgress)
API to display progress from the server on the client side. This means
server initiated restores no longer need any custom client code, and the
server can choose when to display a UI without a client code change.

This did require a bit of complex code to handle either the server or
client cancelling the request.

Additionally, we still have custom requests for manually initiated
restores from the client.

## Hide restore progress for canonical files
Utilizing the above change, I modified the server behavior to not show
any progress when restoring the canonical file. This is an internal
server operation and does not need to be displayed client side (based on
feedback it only causes confusion).

CLient side change - dotnet/vscode-csharp#8780

Build Branch: refs/heads/release/dev18.3

Internal ID: 20251105.5
Internal VS ID: rel.d18.3-11206.111

File-based programs live directive diagnostics (#80575)

Build Branch: refs/heads/release/dev18.0

Internal ID: 20251029.7
Internal VS ID: rel.d18.0-11205.157

Build Branch: refs/heads/release/dev17.14

Internal ID: 20250812.6
Internal VS ID: rel.d17.14-36705.20

Fix "Introduce local" generating invalid code for function pointer ty…

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Fix "Introduce local" generating invalid code for function pointer ty…

…pes (#80983)

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Fix "Introduce local" generating invalid code for function pointer ty…

…pes (#80983)

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Build Branch: refs/heads/release/dev18.0

Internal ID: 20251029.7
Internal VS ID: rel.d18.0-11201.02

Build Branch: refs/heads/release/dev17.12

Internal ID: 20250126.6
Internal VS ID: rel.d17.12-36631.10