Per LSP spec, when receiving `workspace/diagnostic/refresh`, clients
should refresh all pulled diagnostics including both workspace and
document diagnostics[^1]. Previously, only workspace diagnostics were
refreshed.

[^1]:
https://microsoft.github.io/language-server-protocol/specifications/lsp/3.18/specification/#diagnostic_refresh

This adds `pull_document_diagnostics_for_server()`, which refreshes
`textDocument/diagnostic` for all open buffers associated with the
given language server.

Closes #ISSUE

Release Notes:

- When handling `workspace/diagnostic/refresh`, Zed now also sends new
`textDocument/diagnostic` requests for open files, aligning with the LSP
specification.

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Co-authored-by: John Tur <john-tur@outlook.com>