Unify and Fix Pseudo-Coverage in Example Fuzzers

`static_mut_refs` are going to break soon. This needs fixing. See discussion [here](https://github.com/AFLplusplus/LibAFL/pull/2784#discussion_r1893727318) and [here](https://github.com/AFLplusplus/LibAFL/pull/2770#discussion_r1885707774).

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.