GraalVM rc7 removed method LocalizationSupport#addToCache

[Sanne]

We'll need to figure out a better alternative for Shamrock.

In the meantime when testing things with Graal "master" I've used this additional commit to restore compatibility:

https://github.com/protean-project/graal/commit/581706eb9aaf417646eba6188dbf2eae92d308f0

[stuartwdouglas]

This should actually be pretty easy to fix once RC7 is released, it looks like the method was just renamed. If we want something that works on both then I could add some reflection based thing but I think it might be easier to just wait.