Switch to `sennaar` registry format

[chuigda]

Since sennaar registry format is now somewhat accomplished, we can migrate to sennaar, also in order to give sennaar a good test case.

Despite the jobs to be done, the major difficulty here is to convert more hierarchial CExpr into equivalent Java representation. An idea is to write some fun constEvalTranspile(expr: CExpr): (ResultExprString, dependsOnOtherEnumValuesFromSameEnum, dependsOnOtherEnumsValuesFromOtherValue, dependsOnGlobalConstants).