Warn/error on incompatible Java/Scala version

[stevedlawrence]

Some combinations of versions of Java, Scala, and Daffodil are known to be incompatible. The plugin should error or have a prominent warning when this is the case.

Known/documented incompatibilities:

// Compatible version sets include:
// Java 8, 11, Scala 2.12.11 (exactly), Daffodil 3.0.0 (and below)
// Java 8, 11, 17, Scala 2.12.15 (and above), Daffodil 3.1.0 (and above)
// cannot be java 17 with daffodil 2.7.0 and scalaVersion 2.12.11.

Note that we should only error on known incompatibilities so we can still test with new versions, even if they are not yet known to be compatible. If we later determine new versions are incompatible then we can update the plugin.

[stevedlawrence]

Another discovered compatibility issue is Java 21 requires scala 2.12.18 or newer. This is confirmed by the scala compatibility chart here:

https://docs.scala-lang.org/overviews/jdk-compatibility/overview.html

[mbeckerle]

Another discovered compatibility issue is Java 21 requires scala 2.12.18 or newer. This is confirmed by the scala compatibility chart here:

https://docs.scala-lang.org/overviews/jdk-compatibility/overview.html

So, should the sbt-daffodil plugin also be specifying the default scala version then? My guess is this whole matrix of java/scala/daffodil compatibility is too complex to leave dribs and drabs of it in every schema's build.sbt file.

[stevedlawrence]

Probably. I opened #34 to consider providign a default scala version. We still might want this warning/error since a project could always override it the setting.