Returns allocations, newest first. An allocation is a holding set aside for a named
settlement: the owner commits a specific amount of a specific instrument to a
specific transfer leg, and it stops being spendable until the settlement executes
or the allocation is released.

This is the mechanism behind locked on /token/positions. A position's
locked quantity is the sum of its allocated holdings, and this endpoint is what says
why each one is locked and to whom it is committed. If a customer asks why funds
appear unavailable, this is the answer.

settlementId is the join key. It appears on the DvP that requested the allocation
and on every allocation funding it, so the two sides of a settlement can be assembled
without following contract identifiers.

Two deadlines, and missing either fails the settlement.
allocationDeadlineAt is when every leg must be allocated; a settlement with any leg
unallocated past that instant cannot proceed. settlementDeadlineAt is when execution
must have happened. Both come from the settlement's own terms rather than from this
allocation, so all legs of one settlement carry the same pair — which makes them
useful for a countdown, and useless for telling legs apart.

state spans three distinct record types the standard uses in sequence — a request
addressed to the owner, an instruction in progress, and the committed allocation
itself. Only allocated locks the holding.