fix(neovim): use getnixpath util for nvim-dap and lsp, move polish

This moves polish.lua to `lua/`, creates a util.lua file to be loaded
before lazy.nvim so we can use the `getnixpath` util everywhere, and
replaces in polish.lua and lsp.lua the template strings for substitution
with a `getnixpath` equivalent

modules/home-manager/programs/neovim/lsp.lua

@@ -104,7 +104,8 @@ return {
               globalPlugins = {
                 {
                   name = "@vue/typescript-plugin",
-                  location = "{pkgs.vue-language-server}/lib/node_modules/@vue/language-server",
+                  location = vim.fn.getnixpath "vue-language-server"
+                      .. "/lib/node_modules/@vue/language-server",
                   languages = { "vue" },
                   configNamespace = "typescript",
                   enableForWorkspaceTypeScriptVersions = true,