Add support for postgres R2DBC in the java agent

[petergphillips]

We've looking at switching from using JDBC to using a completely reactive stack and using R2DBC with postgres instead.

Using JDBC we had all of the database calls logged as dependencies. This no longer happens when using R2DBC.

It looks like you might support mongo R2DBC (according to https://docs.microsoft.com/en-us/azure/azure-monitor/app/java-in-process-agent#autocollected-dependencies) already, but can't see any support for other flavours.

Please could you therefore consider supporting R2DBC using postgres. I can see our requests come through so you currently support netty and webflux, so would be good to add support for the whole stack.

[trask]

This is tracked at https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues/2515, we will pull into Application Insights once it is available upstream

[trask]

Instrumentation for r2dbc has just been added upstream in https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues/2515

[trask]

Preview instrumentation for r2dbc is now available in the latest Application Insights Java version: https://learn.microsoft.com/en-us/azure/azure-monitor/app/java-standalone-config#preview-instrumentations