Allow migration of maxCodeSizeConfig to transitions.contractsizelimit

[vdamle]

• Require genesis to specify max contract size using Transitions config.
• Add checks to allow migrating from a prior maxCodeSizeConfig to contractsizelimit specified in Transitions config.
• NOTE: Remove support for legacy max code size genesis configuration by rejecting genesis config that specifies only maxCodeSizeConfig or maxCodeSize and maxCodeSizeChangeBlock.
• cosmetic enhancement to a log message on startup to include Transitions since this is useful information for node operators.

FYI, given that the notice to use Transitions in lieu of the legacy max code size config parameters has been advertised for more than a year, I felt that it is not premature to remove support for it.

Fixes: https://github.com/ConsenSys/quorum/issues/1622