Allow searching and display of modules not offered in the current AY

NUS Bulletin's Search Modules page will be removed in July, and NUSMods is to take over this functionality for the university.

However, NUSMods currently does not show modules which are not offered in the system, an essential feature. We accomplish this by ignoring all modules which do not have timetables. This was done because there was no need to show non-offered mods. However RO has since told us that:

The reason why we may need a comprehensive listing of active modules in NUSMods (including those that haven’t been timetabled) is because students may wish to e.g. map a module they have taken while on SEP back to NUS.

TODO

• Modify scraper to process all mods, even if they're not offered in the AY (#1776)
• Modify website to search through all 11+k modules. This will require an overhaul of the module search page as the current offline search is not scalable for longer - it currently downloads 5+MB of data (for ~5.5k mods) when the module page is loaded, and the new combined offered+non-offered mods list is over 10MB in size. Also, searching through more modules will require more computational power that weaker devices will not be able to support.