Unify and Fix Pseudo-Coverage in Example Fuzzers

[riesentoaster]

static_mut_refs are going to break soon. This needs fixing. See discussion here and here.

Additionally, handling of the pseudo-coverage is different between example fuzzers. The names, the extraction of necessary data from the static array, and the way the data is passed to the observers should be unified.

[langston-barrett]

These should probably also be updated to use a Vec in a RefCellValueObserver so that they can be implemented in safe Rust.