feat(lsp): send didChangeConfiguration after init (#18847)

Most LSP servers require the notification to correctly load the
settings and for those who don't it doesn't cause any harm.

So far this is done in lspconfig, but with the addition of vim.lsp.start
it should be part of core.

runtime/lua/vim/lsp.lua

@@ -1117,6 +1117,10 @@ function lsp.start_client(config)
         end
       end
 
+      if next(config.settings) then
+        client.notify('workspace/didChangeConfiguration', { settings = config.settings })
+      end
+
       if config.on_init then
         local status, err = pcall(config.on_init, client, result)
         if not status then