feat(api/v2): ⭐ Implement application routes

[Nudelsuppe42]

[1] Feature Description
get /applications
post /applications -> create application for a user
get /applications/[appId]
put /applications/[appId] -> review applications \

get /applications/questions
get /[teamId]/applications/questions
post /applications/questions
put /applications/questions -> also needs to support adding new ones (upsert)
put /applications/questions/[questId]
del /applications/questions/[questId] \

get /applications/templates
post /applications/templates
put /applications/templates/[tempId]
del /applications/templates/[tempId]