Fixes#36818
Release Notes:
- Added new `global_lsp_settings.request_timeout` setting to configure
the maximum timeout duration for LSP-related operations.
Code inspired by [prior
implementation](https://github.com/zed-industries/zed/pull/38443),
though with a few tweaks here & there (like using `serde:default` and
keeping the pre-defined constant in the LSP file).
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Co-authored-by: Kirill Bulatov <mail4score@gmail.com>
Co-authored-by: Kirill Bulatov <kirill@zed.dev>