Including the blinded path incoming channel list argument to the
addinvoice command, parsing and verifying that it has one or a
comma separeted list of channels id.
We want to export some of our CLI code to re-use in other projects. But
in Golang you cannot import code from a `main` package.
So we need to move the actual code into its own package and only have
the `func main()` in the `main` package.
