Function into_consolidatable_updates_startup

pub(crate) fn into_consolidatable_updates_startup(
    updates: Vec<StateUpdate>,
    ts: Timestamp,
) -> Vec<(BootstrapStateUpdateKind, Timestamp, Diff)>

Convert updates into a Vec that can be consolidated by doing the following:

• Convert each update into a type that implements std::cmp::Ord.
• Update the timestamp of each update to the same value.
• Convert the diff of each update to a type that implements differential_dataflow::difference::Semigroup.

mz_catalog::memory::objects::StateUpdateKind does not implement std::cmp::Ord only because it contains a variant for temporary items, which do not implement std::cmp::Ord. However, we know that during bootstrap no temporary items exist, because they are not persisted and are only created after bootstrap is complete. So we forcibly convert each mz_catalog::memory::objects::StateUpdateKind into an BootstrapStateUpdateKind, which is identical to mz_catalog::memory::objects::StateUpdateKind except it doesn’t have a temporary item variant and does implement std::cmp::Ord.

WARNING: Do not call outside of startup.