goalc/repl: cleanup of goalc/REPL code and some QoL improvements (#2104)

- lets you split up your `startup.gc` file into two sections
  - one that runs on initial startup / reloads
  - the other that runs when you listen to a target
- allows for customization of the keybinds added a month or so ago
- removes a useless flag (--startup-cmd) and marks others for
deprecation.
- added another help prompt that lists all the keybinds and what they do

Co-authored-by: water <awaterford111445@gmail.com>

common/versions.cpp

@@ -29,3 +29,7 @@ std::string version_to_game_name(GameVersion v) {
       ASSERT_MSG(false, fmt::format("no game_name for version: {} found", fmt::underlying(v)));
   }
 }
+
+std::vector<std::string> valid_game_version_names() {
+  return {game_version_names[GameVersion::Jak1], game_version_names[GameVersion::Jak2]};
+}