Node type aware load balancing

[HarshDaryani896]

IDEA: IDEA-1197

Implementation details: Doc

The connection property loadBalance currently allows only two values, viz. false (the default) and true.

It will now also allow below five new values to be specified:
only-rr - Create connections only on Read Replica nodes
only-primary- Create connections only on primary cluster nodes
prefer-rr - Create connections on Read Replica nodes. If none available, on any node in the cluster including primary cluster nodes
prefer-primary - Create connections on primary cluster nodes. If none available, on any node in the cluster including Read Replica nodes
any - Equivalent to value true. Create connections on any node in the primary or Read Replica cluster

default value is still false

Other Minor changes:

• Added the following 2 new connection properties: fallbackToTopologyKeysOnly and failedHostReconnectDelaySecs

Testing:
Test cases identified and listed in this doc.
Test for all test cases listed in the doc added to driver-example repo: PR LINK.
Ran the existing and new tests in driver examples repo for node-postgres.