Instrumentation of NestJS functional middleware

[nicohrubec]

https://docs.nestjs.com/middleware#functional-middleware

Currently we have auto instrumentation for class based middleware. To do that we hook into the @Injectable decorator and patch the implemented use method on the class. However, nest also allows to add middlewares that are vanilla functions via app.use or the MiddlewareConsumer. These functional middlewares can be manually decorated with SentryTraced to get instrumentation but it would be better to have them auto-instumented.