* validator_discovery: less flexible, but simpler design

* fix test

* remove unused struct

* smol optimization

* validator_discovery: basic retrying logic

* add a test

* add more tests

* update the guide

* more test logic

* Require at least 2/3 connectivity.

* Fix test.

* Update node/network/gossip-support/src/lib.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* Update node/network/gossip-support/src/lib.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

Co-authored-by: Robert Klotzner <robert.klotzner@gmx.at>
Co-authored-by: Robert Klotzner <eskimor@users.noreply.github.com>
Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>