Start 2.0 dev work on some of our other modules (pekko-http, pekko-connectors, etc.)

[pjfanning]

Related to #1956 but focusing on modules like pekko-http, pekko-connectors.
I would not make any downstream modules dependent on unreleased changes in the Pekko core but there might be a benefit to starting the work on removing Java 8 support (and Scala 2.12 support if that is agreed to be a 2.0 aim).
With Java 17 a min, we could remove a number of ScalaSteward conf settings to block us from uptaking newer jars. Spring is an example where Java 17 is now the min supported version for the latest release.
We could also look at removing uses of sun.misc.Unsafe if there are any left.
I wouldn't suggest that we start 2.0 dev in all repos but pekko-http and pekko-connectors are 2 that look like it could be useful.

[mdedetrich]

So we really need to discuss the deal with binary compatibility for Pekko 2.0.x before looking at satellite projects. If we have no binary compatibility guarantees for Pekko 2.0.x (which should be the case, this is what is standard practice for SemVer + Java/Scala/Kotlin libraries) then what I would suggest is we do the first round of major breaking changes for Pekko 1.0.x i.e.

• JVM 1.7
• Remove all deprecated code
• Unsafe to VarHandle changes
• Upgrade library dependencies to latest epoch version (some are stuck on older epoch versions because we are stuck on JDK 8)

And then at that point we would release a Pekko 2.0.0-M0 . We can start propagating down the dependency graph doing similar changes and then releasing 2.0.0-M0 for those satellite projects.