feat(lsp): show server version in :checkhealth #31611

Problem:
Language server version information missing from `:checkhealth vim.lsp`.

Solution:
Store `InitializeResult.serverInfo.version` from the `initialize`
response and display for each client in `:checkhealth vim.lsp`.

runtime/lua/vim/lsp/client.lua

@@ -174,6 +174,10 @@ local validate = vim.validate
 --- capabilities.
 --- @field server_capabilities lsp.ServerCapabilities?
 ---
+--- Response from the server sent on `initialize` describing information about
+--- the server.
+--- @field server_info lsp.ServerInfo?
+---
 --- A ring buffer (|vim.ringbuf()|) containing progress messages
 --- sent by the server.
 --- @field progress vim.lsp.Client.Progress
@@ -556,6 +560,8 @@ function Client:initialize()
       self.offset_encoding = self.server_capabilities.positionEncoding
     end
 
+    self.server_info = result.serverInfo
+
     if next(self.settings) then
       self:notify(ms.workspace_didChangeConfiguration, { settings = self.settings })
     end