[1.x] TDB (iproto): working with failover coordinator

**Product:** Tarantool DB
**Since:** 1.2.4
**Root documents:** 
- https://www.tarantool.io/en/tarantooldb/doc/1.x/install_and_upgrade/install/#install-requirements
- https://www.tarantool.io/en/tarantooldb/doc/1.x/reference/roles/#failover-coordinator

**SME:** @ a1div0 

# Details

MR: https://gitlab.corp.mail.ru/tarantool/tdb/tarantooldb/-/merge_requests/102

See sub issues for details: