feat: Prevent creating multiple fidelity bonds with same expiry date

[theborakompanioni]

This request stems from a user suggestions. Thank you, btw :pray:

As the title says, as Jam is tailored towards non-expert users, address reuse should be prevented (as much as possible) when creating fidelity bonds . Since the address of the bond is shown beforehand, if someone really wants to do this - for whatever reason - it can still be done manually or by using the CLI. However, the UI should try to stop this from happening if possible.

Out of scope: Since Jam does not know any historical, expired (and subsequently moved) fidelity bonds, recreating FB with the same expiry date afterwards cannot be prevented. However, should it be prevented to create multiple FBs in the first place?