[K8SPS-643] Add support of Hybrid replication

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Tell us about the feature
We need to add the possibility of deploying hybrid replication for the PS operator.

Which product(s) is this request for?
Operators MySQL

Tell us about the problem
We have an idea to use GR as a primary cluster (for write traffic only or optional), and users will be able to secure pods as an async replication for read traffic.
`
Read traffic: ONLY from Async Replica pods. NOT from GR replicas.

                         Application (writes / reads)
                                    |
                         +----------v----------+
                         | Proxy (HAProxy)     |
                         | :3306 = writes only |
                         | :3307 = reads only  |
                         +----------+----------+
                                    |
              +---------------------+-----------------------+
              |                                             |
    writes (3306)                          reads (3307) — ONLY to Async Replica pods
              |                                             |
              v                                             |
              |                                             v
   +------------------+  +------------------+     +------------------+  +------------------+  +------------------+
   | GR Primary       |<->| GR Replica 1..2 |     | Async Replica    |  | Async Replica    |  | Async Replica    |
   | (writes only)    |   | (writes only)   |     | pod 1 (READS)    |  | pod 2 (READS)    |  | pod N (READS)    |
   +--------+---------+   +------------------+     +------------------+  +------------------+  +------------------+
             |                                              ^                    ^                  ^
             | async replication (binlog)                   |                    |                  |
             +-----------------------------------------------------------------------------------------------+

`