Merge branch 'en/ort-perf-batch-10'

Various rename detection optimization to help "ort" merge strategy backend. * en/ort-perf-batch-10: diffcore-rename: determine which relevant_sources are no longer relevant merge-ort: record the reason that we want a rename for a file diffcore-rename: add computation of number of unknown renames diffcore-rename: check if we have enough renames for directories early on diffcore-rename: only compute dir_rename_count for relevant directories merge-ort: record the reason that we want a rename for a directory merge-ort, diffcore-rename: tweak dirs_removed and relevant_source type diffcore-rename: take advantage of "majority rules" to skip more renames