Pull down all non-code notes (#14)

This commit changes the filter on the API response so that we are only
filtering out system level notes. This means we get notes that are not
linked to specific locations in the code.

Subsequent work will have to separate these types of notes from the
other code-linked notes and probably display them in some sort of
separate tree.

lua/gitlab/utils/init.lua

@@ -131,7 +131,7 @@ end
 
 
 local function jump_to_file(filename, line_number)
-  if line_number == nil then line_number = 1 end
+  if line_number == nil or filename == nil then return end
   vim.api.nvim_command("wincmd l")
   local bufnr = vim.fn.bufnr(filename)
   if bufnr ~= -1 then