Configure ROB prefetching in newJO [ATR-28500]

The final configuration of ROB prefetching with the chain filters was missed from the CA menu generation. This MR adds it in, with adaptations of the logic to extract the chain hashes so that a single implementation can be used for both legacy and CA, with only the final step of the alg configuration being factorised.

When legacy goes away we can simplify some of the bits that are just there for backwards-compatibility e.g. getChildren vs Members.

Spotted from ATR-28500 JO diff for data.