Gather feedback on printing proofs to stdout

[phated]

In #1992, we removed the ability for nargo prove to print a proof on stdout and instead it is always saved to the filesystem.

We are looking for feedback on this change. Do you have any uses cases that would need the proof printed on stdout?

[Savio-Sou]

cc @critesjosh @signorecello

[critesjosh]

I haven't encountered a need for it to be printed.

[critesjosh]

I've heard devs find it confusing that nargo prove x does not print anything when it runs successfully. Maybe printing something like "Proof ran successfully in X ms. Stored at target/x.json." on a successful run would help reduce confusion.

[signorecello]

I agree with @critesjosh we should give some feedback when proving, currently it just hangs and it can be confusing. For example, if it needs to download the backend and my connection is slow, I'm left in the dark on what exactly is happening.

@Savio-Sou can we reopen?

[Savio-Sou]

Those sound like two new Issues versus this (printing the proof upon proving).

Instead of reopening, @signorecello could you help create two new ones for:

1. Add successful message for nargo prove and nargo verify
2. Add downloading message in Nargo for backend and SRS downloads