Add Mobility page for ISBs, MRT info

[kagiura]

https://github.com/kagiura/nusmods/tree/kagiura/mobility

TODO: immediate:

• [x] replace with proxy API url
• [x] placeholders for when no bus data / no buses left today
• [x] svc E placeholder (make it show "resumes later today")
• [x] actually make it register if its term or holiday (in getServiceStatus (src/utils/mobility.ts))
• [x] update bus schedule
• [x] button to switch to opposite side stop
• [ ] directional arrows for one way svc
• [x] optimize: use useCallback/useMemo
• [x] auto-switch to BTC when needed (and vice versa)
• [x] fix text font size for selected/focused stop

future:

• [ ] show KR / BG MRT timings too why not
• [ ] make it just use a normal polyline so its easier (?) to update when route changes
• [ ] locate nearby classrooms

[kagiura]

refactored a fck ton + this shows properly whether there actually is no more buses or there was an error

[kagiura]

(also, its kind of annoying to take out the keys manually every time i wanna commit so ill wait until proxy api is set up before i continue with timings-related features haha)

[kagiura]

(minor update: MRT timings do not exist as a public api in singapore :,)

[kagiura]

optimization checklist

• [x] MobilityContainer
• [x] SvcDetail
• [x] SvcList
• [x] StopDetail
• [x] LocationMap
• [x] ISBServices

[aoi-ue]

@kagiura are those to-do fully completed? seems like the pipeline is failing because some build issue (cicd issue seems like it) would like to contribute on this.