fix(lspinfo)!: remove config.lspinfo

Problem:
`config.lspinfo` is an undocumented feature that allows extending the
info shown in `:LspInfo` (`:checkhealth lspconfig`).
This feature is unwanted because:
- it's undocumented
- it adds a maintenance burden
- it provides info that should be derived from the LSP protocol itself.

Solution:
Remove support for `config.lspinfo`.
Instead, `:LspInfo` (`:checkhealth lspconfig`) should be enhanced to
automatically gather this kind of extra info from the server response.

Author: justinmk

doc/configs.md

@@ -5592,10 +5592,6 @@ require'lspconfig'.hls.setup{}
   ```lua
   { "haskell", "lhaskell" }
   ```
-  - `lspinfo` : 
-  ```lua
-  see source file
-  ```
   - `root_dir` : 
   ```lua
   root_pattern("hie.yaml", "stack.yaml", "cabal.project", "*.cabal", "package.yaml")

doc/configs.txt

@@ -5592,10 +5592,6 @@ require'lspconfig'.hls.setup{}
   ```lua
   { "haskell", "lhaskell" }
   ```
-  - `lspinfo` : 
-  ```lua
-  see source file
-  ```
   - `root_dir` : 
   ```lua
   root_pattern("hie.yaml", "stack.yaml", "cabal.project", "*.cabal", "package.yaml")

lua/lspconfig/configs/hls.lua

@@ -12,22 +12,6 @@ return {
         cabalFormattingProvider = 'cabalfmt',
       },
     },
-    lspinfo = function(cfg)
-      local extra = {}
-      local function on_stdout(_, data, _)
-        local version = data[1]
-        table.insert(extra, 'version:   ' .. version)
-      end
-
-      local opts = {
-        cwd = cfg.cwd,
-        stdout_buffered = true,
-        on_stdout = on_stdout,
-      }
-      local chanid = vim.fn.jobstart({ cfg.cmd[1], '--version' }, opts)
-      vim.fn.jobwait { chanid }
-      return extra
-    end,
   },
 
   docs = {

lua/lspconfig/health.lua

@@ -174,11 +174,6 @@ local function make_client_info(client, fname)
     'autostart:       ' .. client_info.autostart,
   }
 
-  if client.config.lspinfo then
-    local server_specific_info = client.config.lspinfo(client.config)
-    info_lines = vim.list_extend(info_lines, server_specific_info)
-  end
-
   vim.list_extend(lines, info_lines)
 
   return table.concat(lines, '\n')