nvim/lsp: enable GN language server

Using my own fork of nvim-lspconfig [1] for now, until my PR gets merged
upstream.

[1] https://github.com/nickdiego/nvim-lspconfig/tree/gnls
[2] neovim/nvim-lspconfig#3773

Signed-off-by: Nick Diego Yamane <nickdiego@igalia.com>

Author: nickdiego

config/nvim/lua/config/lsp.lua

@@ -86,6 +86,10 @@ lspconfig.mesonlsp.setup {
   on_attach = on_attach,
 }
 
+lspconfig.gnls.setup {
+  on_attach = on_attach,
+}
+
 -- Diagnostic configs
 vim.diagnostic.config({
   signs = false,

config/nvim/lua/plugins.lua

@@ -55,7 +55,7 @@ return {
   { 'tpope/vim-fugitive' },
   { 'rhysd/committia.vim' },
   { 'chromium/vim-codesearch' },
-  { 'neovim/nvim-lspconfig' },
+  { 'nickdiego/nvim-lspconfig' },
 
   -- completion
   { 'hrsh7th/nvim-cmp',