Each route a function

[leomp12]

Is your feature request related to a problem? Please describe.
Is harder to debug Cloud Functions with all routes ate the same Express server, also it may produce slower starts.

Describe the solution you'd like
Each app route should be exported as a different Cloud Function.

Describe alternatives you've considered
If using Cloud Run #138 may be useful to keep a server with all (or almost) routes, in this case just may be better to use https://www.fastify.io/ in place of current Express implementation.

Additional context
Also related to #136