Do not load all persistence libraries unless needed

[yiminc]

Currently, we load all persistence libraries no matter what persistence the server is configured to run with. With recent added auth plugin, we are now also pull in aws libraries for "rds-iam-auth". This will quickly become unsustainable.

We need a better way to be able to load only needed libraries. Few options I can think of:

• Build plugins as library and load dynamically at runtime based on persistence config.
• Use different build flag to include only needed libraries at build time for persistence used. This will result in different binaries for different persistence.