feat(grpc): Add initial Getinfo grpc

[oxarbitrage]

Motivation

We want to get started with the grpc methods by adding a first dummy call that will work as the framework to add other more interesting ones.

Part of #8162

Depend on #8167

PR Author Checklist

Check before marking the PR as ready for review:

• Will the PR name make sense to users?
• Does the PR have a priority label?
• Have you added or updated tests?
• Is the documentation up to date?

Solution

I followed the hello world example of tonic (https://github.com/hyperium/tonic/blob/master/examples/helloworld-tutorial.md) and adapted to our needs.

Access to the scanner database will be done by a service at #8185 . We want to add some real info to this method after that.

This is the most basic and smaller piece i was able to build.

Testing

No testing was done here, only manual testing.

In the server side the grpc endpoint can be started with:

cargo run --bin scanner-grpc-server

Then the client can make a call with:

$grpcurl -plaintext -import-path ./proto -proto scanner.proto '[::1]:50051' scanner.Scanner/GetInfo
{
  "minSaplingBirthdayHeight": 419200
}
$ 

I think we should make tests by using client code at https://github.com/hyperium/tonic/blob/master/examples/helloworld-tutorial.md#writing-our-client

Review

I think anyone that will be working in the grpc methods we are about to develop can review.

Reviewer Checklist

Check before approving the PR:

• Does the PR scope match the ticket?
• Are there enough tests to make sure it works? Do the tests cover the PR motivation?
• Are all the PR blockers dealt with?
  PR blockers can be dealt with in new tickets or PRs.

And check the PR Author checklist is complete.

Follow Up Work

• Create test
• Run with zebra instead of separated binary
• Add configuration (endpoint socket/addr, port, etc).
• Decide what to add that is actually useful in the getinfo response.

[oxarbitrage]

Looks good, i am not really sure if the failing test is related to this PR. https://github.com/ZcashFoundation/zebra/actions/runs/7661775200/job/20881794125?pr=8178

[arya2]

Looks good!