Implement new setup key resource (#178)

This change implements a new resource called SetupKey that manages the
lifecycle of setup keys and stores them in secrets.

A major change here is that we are also switching to using SSA for
resource management.

Part of #172

Signed-off-by: Philip Laine <philip.laine@gmail.com>

Dockerfile

@@ -17,6 +17,7 @@ RUN go mod download
 COPY cmd/main.go cmd/main.go
 COPY api/ api/
 COPY internal/ internal/
+COPY pkg/ pkg/
 
 # Build
 # the GOARCH has not a default value to allow the binary be built according to the host where the command