feat(jedi.lua): enable call signatures in Jedi completion popup and configure Jedi to use spaces instead of tabs for indentation

feat(supertab.lua): add Supertab plugin and configure it to be loaded after Absolute configuration

lua/absolute/after/jedi.lua

@@ -1,5 +1,7 @@
-
 vim.g["jedi#popup_on_dot"] = 1
+vim.g["jedi#use_tabs_not_buffers"] = 0
+vim.g["jedi#popup_select_first"] = 0
+vim.g["jedi#show_call_signatures"] = "2"
 
 
 -- Keybindings
@@ -12,4 +14,3 @@ vim.g["jedi#usages_command"] = "<leader>n"
 vim.g["jedi#completions_command"] = "<C-Space>"
 vim.g["jedi#rename_command"] = "<leader>rn"
 vim.g["jedi#rename_command_keep_name"] = "" -- "<leader>R"
-