FR - Support switchover role read-write

[minhnguyenvan95]

Is your feature request related to a problem? Please describe.
I wan't pgcat automatic switchover read/write role when patroni promote new leader

Describe the solution you'd like
patroni have healthcheck api that return the ipaddress for write role, we should have some passive healthcheck feature for write role

Describe alternatives you've considered
I already used HAProxy with keepalive to determine new write role node but the performance decrease like 20% for TPS and latency