Investigate other proxy mechanisms

[mostafa]

With the removal of the elastic proxy mechanism in #359, there is currently a single proxy type that connects incoming connections to a limited set of connections (in the available connections pool). The idea here is to investigate other proxy mechanisms, for example, one is being developed in #398 (#512, #577, #587, #588, #590, #591, #592 and #599) to enable multiple proxies to be connected to a single server instance to allow routing between multiple database servers. This enable advanced proxying (#337) and routing (#399). These are the objectives:

• 1. List different proxy mechanisms in similar products (see Feature parity with proxies #206)
• 2. Analyze them to find appropriate proxy mechanisms for GatewayD
• 3. Write a report based on the analysis
• 4. Create tickets (epics and others) for the chosen mechanisms