update `fpr_xref_crossings` to include `bt_spawning_km` and `bt_rearing_km`

[NewGraphEnvironment]

guessing this was a perhaps due to a poor previous xref table design decision

[NewGraphEnvironment]

hmmm. this is a proper messy due to https://github.com/NewGraphEnvironment/fish_passage_template_reporting/issues/1

see commits to close NewGraphEnvironment/fish_passage_fraser_2023_reporting#144 as a temporary workaround. Can likely build fpr_xref_crossings the same as is done in those commits (or filter and join tribble object in scripts/tables.R scripts of repos) and filter reports based on species present in the study areas.