Adapt to go 1.16

[bastianccm]

Go 1.16 brings a lot of nice enhancements, so we should evaluate if we can adapt them.

NotifyContext

https://tip.golang.org/pkg/os/signal/#NotifyContext

flamingo/framework/cmd/module.go

Lines 42 to 44 in ce166cf

	signals := make(chan os.Signal, 1)
	shutdownComplete := make(chan struct{}, 1)
	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)

embed

https://tip.golang.org/pkg/embed/
(not used yet, but might be useful to integrate something?)

metrics

https://tip.golang.org/pkg/runtime/metrics/
We should investigate how this extends/replaces opencensus/opentelemetry #179