Split cardano-shelley-ma into two Allegra and Mary

Current implementation of ShelleyMA is unlike all other eras and is quite awkward and sometimes gets into way of implementing new features.

The plan is to:

* [x] - (done in #3175) Split `cardano-ledger-shelley-ma` into `cardano-ledger-allegra` and `cardano-ledger-mary`
* Keep `cardano-ledger-shelley-ma` for a while with some deprecations instructions how to transition to new packages. Breakage should be minimal
* Get rid of `ShelleyMA ma era` type and `MAClass` class as no longer useful
* [ ] - Move `cardano-ledger-shelley-ma-test` functionality into `testlib` sublibraries in the `cardano-ledger-allegra` and `cardano-ledger-mary`