refactored and switched to config with packer

lua/config/theme.lua

@@ -1,19 +0,0 @@
--- color scheme
-vim.g.onedark_config = { style = 'darker' }
-vim.cmd('colorscheme onedark')
-
--- highlight extra white space with red
-vim.api.nvim_set_hl(0, 'TrailingWhitespace', { ctermbg = 'red', bg = '#ff5555' })
-vim.cmd([[match TrailingWhitespace /\s\+$/]])
-
--- diagnostics
-local signs = { Error = " ", Warn = " ", Hint = " ", Info = " " }
-for type, icon in pairs(signs) do
-    local hl = "DiagnosticSign" .. type
-    vim.fn.sign_define(hl, { text = icon, texthl = hl, numhl = hl })
-end
-
-vim.diagnostic.config({
-    virtual_text = { prefix = '●' };
-})
-