chore: More detailed logs why an order got filtered out

[MartinquaXD]

Background

Orders where the user doesn't have the required "effective balance" get filtered out. The effective balance here means min(token_allowance, token_balance) because the settlement contract can only spend this much money of the user.

At the moment we don't differentiate between missing balances and missing allowances and always report insufficient_balance.

Details

It would be nice to make the SolvableOrdersCache aware of allowance, balance and effective_balance to improve the logs.

Implementation suggestions:
Make BalanceFetching::get_balances() return what's currently account_balances::simulation::Simulation which already contains all the necessary information.
Change solvable orders cache to filter based on effective_balance and either report insufficient_balance or insufficient_allowance based on the respective values (balance should have higher prio).
In term of order_events I would still only store insufficient_balance to not over-complicate this in the DB.

[github-actions]

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