Expanse Byzantium update w/ correct metropolis difficulty increment divisor (#7463)

* Byzantium Update for Expanse

Here the changes go. Hope I didnt miss anything.

* expip2 changes - update duration limit

* Fix missing EXPIP-2 fields

* Format numbers as hex

* Fix compilation errors

* Group expanse chain spec fields together

* Set metropolisDifficultyIncrementDivisor for Expanse

* Revert #7437

* Add Expanse block 900_000 hash checkpoint