Resolve eon index / keyper set index ambiguity

[jannikluhn]

The keyper set index is the index of a keyper set in the keyper set manager contract. The eon index is the index of a eon DKG process. Normally, the two indices should be the same. However, they can diverge in the following situations:

• If the eon DKG fails. Then, Shuttermint will run another DKG with incremented eon index.
• The Shuttermint chain has an InitialEon genesis parameter. If this index doesn't match the index of the initial keyper set, eon and keyper set index are likely different.

In some places in the code we assume they are the same. This results in errors. We need to

1. Identify the places in which we use the keyper set index instead of the eon index and vice versa.
2. In those places, translate one into the other. This can be done using the eons table in the keyper db which stores all eon indices with corresponding keyper set index. Adding a query to select the highest eon for a given keyper set index might be useful.

[jannikluhn]

Setting InitialEon to a high value does not trigger this bug.

[jannikluhn]

Fixed as far as we know