feat: Fake epoch execution at API level

[mustermeiszer]

Description

Currently, issuers have the problem that they do not see the effect closing an epoch has on their pool.
For this reason it would be greatly beneficial to fake the epoch execution on the api level and return a nice overview of the new state.

Research/based on

• Issues issuer had with unwanted dropping token prices and hard/impossible to revert invest/redeem order execution due to that.

What are foreseen obstacles or hurdles to overcome?

• on-chain logic potentially blocked due to outdated oracles → need to be able to provide them to the api and force update the values
• on-chain logic potentially closing an epoch but not executing it due to needing a valid solution → need to be able to provide a solution and use it directly
• define structure to be returned that summarizes the new pool state