Feature: use precompiled jars for jazzer

[eustas]

In CI it takes about 2m15s for jazzer rules to compile itself. With precompiled jars only a little bit of native libs are required to be compiled.

[fmeum]

Could you explain a bit more about why this is a problem with your CI setup? Are you using a disk cache?

With a disk cache, Bazel would cache Jazzer after building it once. This would mean that the first CI run using rules_fuzzing would take about 2 minutes longer, but all subsequent runs should just use the cached build of Jazzer.