Fix LSP and update plugins

- Structure LSP configuration code
- Since `lsp-zero` is deprecated, instead use `nvim-lspconfig`
- Use `nvim_lsp_signature_help` instead of `lsp_signature`

nvim/lua/config/editor.lua

@@ -3,9 +3,12 @@ vim.opt.softtabstop = 4
 vim.opt.shiftwidth = 4
 vim.opt.expandtab = true
 vim.opt.smartindent = true
+
 vim.opt.nu = false
 vim.opt.relativenumber = true
+
 vim.opt.wrap = false
+
 vim.opt.termguicolors = true
 vim.opt.swapfile = false
 vim.opt.backup = false