Multi DSN per Java Application support

### Problem Statement

I have a use case where I'd like to separate Projects by team with multiple DSNs in a single JVM application. I tried local testing of a workaround solution (https://github.com/getsentry/sentry-java/compare/feat/multi-dsn-playground) with custom ITransportFactory and EventProcessor which seemed to work. The only issue was that `RequestDetailsResolver` was package-private in the SDK, so my application didn't have access and I had to rewrite my own RequestDetailsResolver, DSN classes. `+ SentryClient.SENTRY_PROTOCOL_VERSION` within the RequestDetailsResolver was also unaccessible, so I have to hardcode the protocol version.

### Solution Brainstorm

Is it possible to make this class public?
https://github.com/getsentry/sentry-java/blob/main/sentry/src/main/java/io/sentry/RequestDetailsResolver.java#L10