Investigate ways to improve the compilation environment on macOS

[jesse-gallagher]

Currently, AbstractEquinoxTask copies tools.jar from the current JVM into the Notes bundle in order to have a working compilation environment. This has never been great, but it's particularly problematic when compiling with Java versions >8, which don't have a tools.jar as such.

It may be better to do similar to what the Open Liberty Runtime does and download an AdoptOpenJDK build of Java 8 as needed and use that, copying in the Notes.jar and websvc.jar from Notes.app or referencing them in the launch classpath. That'd be cumbersome, but it should be reliable at least until the AdoptOpenJDK URLs change (which they may with the move to Adoptium).

[jesse-gallagher]

I investigated using the JDT by way of EclipseCompiler, but it looks like it is limited to working with filesystem-bound dependencies. There was a bug from way back about similar things, but that may have just been about compiling in-memory files (which works) and not about dependencies.