Preload library caches into native-image heap to speed start up

[JaroslavTulach]

Native image has a unique possibility of snapshoting a heap during build time. We can use this functionality to embed cached IRs of certain libraries into the executable.

The analysis of the boot shows that significant amount of time (almost a second) is spent in reading the caches:

We can avoid all of this by loading the IR caches by EnsoLibraryFeature and again even more startup boost.