Move lsp config to local file structure

.config/nvim/lsp/csharp_ls.lua

@@ -0,0 +1,32 @@
+---@brief
+---
+--- https://github.com/razzmatazz/csharp-language-server
+---
+--- Language Server for C#.
+---
+--- csharp-ls requires the [dotnet-sdk](https://dotnet.microsoft.com/download) to be installed.
+---
+--- The preferred way to install csharp-ls is with `dotnet tool install --global csharp-ls`.
+
+local util = require 'lspconfig.util'
+
+---@type vim.lsp.Config
+return {
+  cmd = function(dispatchers, config)
+    return vim.lsp.rpc.start({ 'csharp-ls' }, dispatchers, {
+      -- csharp-ls attempt to locate sln, slnx or csproj files from cwd, so set cwd to root directory.
+      -- If cmd_cwd is provided, use it instead.
+      cwd = config.cmd_cwd or config.root_dir,
+      env = config.cmd_env,
+      detached = config.detached,
+    })
+  end,
+  root_dir = function(bufnr, on_dir)
+    local fname = vim.api.nvim_buf_get_name(bufnr)
+    on_dir(util.root_pattern '*.sln'(fname) or util.root_pattern '*.slnx'(fname) or util.root_pattern '*.csproj'(fname))
+  end,
+  filetypes = { 'cs' },
+  init_options = {
+    AutomaticWorkspaceInit = true,
+  },
+}