Integrate BP update with in-order core

[ABenC377]

          Given it also has inter-unit buffers, should the in-order core also be updated to check for branches in these buffers and flush the branchPredictor if required?

Originally posted by @FinnWilkinson in https://github.com/UoB-HPC/SimEng/pull/401#discussion_r1504137548

There is a plan to overhaul the in-order core. Therefore, integration of the BP update is to be postponed until after this overhaul has taken place to reduce duplication of work.