[Epic] Supervised failover in 3.x

[lenkis]

Related dev. epic: see below
PM ref.: unknown
SME: @ sergepetrenko + @ Totktonada

Details

We received multiple issues related to supervised failover in Tarantool 3.4+.

Main point: now the failover feature works with Tarantool Config Storage (previously -- only with ETCD), and comes together with a failover stateboard.

See comments in related issues for a detailed documentation plan.

Issues

• Supervised failover + Tarantool Config Storage #5334
• Support config.storage as a failover stateboard. #5384
• maybe more to come