lsp: Send client process ID in LSP initialize request (#43988)

Per the [LSP
specification](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#initializeParams),
the client should send its process ID to the language server so the
server can monitor the client process and shut itself down if the client
exits unexpectedly.

Release Notes:

- N/A
4f5cc0a24bShuhei Kadowaki committed on 12/2/2025, 12:04:28 PM· committed by GitHubparenta2f69cd
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