Add Musicoin and MCIP-3 UBI hardfork. (#6621)

* Add musicoin chain spec.

* Add musicoin to parity node

* Add musicoin to the wallet

* Add i18n for musicoin

* Align musicoin chain spec with 1.8, ref #6134

* Update musicoin bootnodes

* Prepare MCIP-3 in musicoin chain spec.

* Update musicoin chain spec with contract addresses for MCIP-3

* Extend ethash params by MCIP-3

* Fix musicoin chain spec json

* Use U256 for block rewards.

* Update musicoin registrar

* Fix merge leftovers

* Update musicoin chain spec for latest master

* Bestow MCIP-3 block reward(s).

* Update musicoin registry once and for all

* Align MCIP-3 block reward with go implementation

* Remove mcip3 test chain spec from repository

* Update MCIP-3 block rewards

* Musicoin homestead transition is at 1_150_000

* Expect mcip3 transtion to be properly defined in chain spec.

* Panic handling for mcip to default to regular block rewards if not specified

* Giving mcip3 rewards a useful default value.

* Fix ethjson tests.

* Update musicoin chain spec

* Fix tests 0:)

* Add musicoin mcip3 era test spec.

* Update musicoin chain spec(s)

* Add tests for mcip3 era block rewards

* Fix tests

* Disable byzantium for musicoin

* Pass miner reward to the tracer.

* Allow modifying blockreward in MCIP-3 transition.