renamed changed lsp names and use web-devicons as a full plugin (#49)

fix #48 

- Renamed LSP servers as they were changed upstream.
- Enable web-devicons as a nixvim plugin instead of installing them as a
extra package.

config/plugins/lsp/lsp.nix

@@ -8,20 +8,20 @@
       inlayHints = true;
       servers = {
         html = {enable = true;};
-        lua-ls = {enable = true;};
-        nil-ls = {enable = true;};
+        lua_ls = {enable = true;};
+        nil_ls = {enable = true;};
+        ts_ls = {enable = true;};
         marksman = {enable = true;};
         pyright = {enable = true;};
         gopls = {enable = true;};
         terraformls = {enable = true;};
-        tsserver = {enable = true;};
         ansiblels = {enable = true;};
         jsonls = {enable = true;};
-        helm-ls = {
+        helm_ls = {
           enable = true;
           extraOptions = {
             settings = {
-              "helm-ls" = {
+              "helm_ls" = {
                 yamlls = {
                   path = "${pkgs.yaml-language-server}/bin/yaml-language-server";
                 };