These refactoring changes are for reducing existing and potential
duplication coming with the addition of new trading protocol support
in the gRPC API.  Some minor styling and logic simplification changes
are also include.

- Convert OfferUtil to injected singleton, and move various offer related
  utility methods into it.

- Delete both MakerFeeProvider classes, which were wrappers around the same
  static old OfferUtil method.

- Inject OfferUtil into CreateOfferDataModel, CreateOfferViewModel,
  TakeOfferDataModel, TakeOfferViewModel, MutableOfferDataModel,
  MutableOfferViewModel, OfferDataModel, EditOfferDataModel,
  EditOfferViewModel

- Refactor TakeOfferViewModel

	Use OfferUtil, remove unused fields & methods.
	Made minor logic simplification, style and formatting changes.

- MutableOfferDataModel

	Made minor logic simplification, style and formatting changes.

- MutableOfferView uses new paymentAccount.isHalCashAccount().

- MutableOfferViewModel

	Refactored to use new VolumeUtil, CoinUtil, OfferUtil.
	Removed unused fields & accessors.
	Made minor style change.

- Refactored OfferDataModel to use new OfferUtil

- Refactor CreateOfferService

	Inject and use OfferUtil
	Move some utility methods to OfferUtil
	Remove unused fields

- Offer

	Refactored to use new VolumeUtil for volume calculations.
	Made stateProperty and errorMessageProperty fields private.

- PaymentAccount

	Moved isHalCashAccount type check to this class.
	Moved getTradeCurrency logic to this class.

- Contract, radeStatistics2, TradeStatistics3

	Refactored to use new VolumeUtil for volume calculations.

- Trade

	Refactored to use new VolumeUtil for volume calculations.
	Made minor logic simplification, style and formatting changes.

- CoinUtil

	Moved some coin utility methods into this class

- CoinUtilTest

	Moved (coin related) tests from CoinCryptoUtilsTest and OfferUtilTest
	into CoinUtilTest, and deleted OfferUtilTest, CoinCryptoUtilsTest.

- Adjust create and edit offer tests to model refactoring

- Add new core.offer.takeoffer.TakeOfferModel

	Would have been nice to move more logic from
	bisq.desktop.main.offer.takeoffer.TakeOfferDataModel,
	but it has JFX dependencies that cannot be use in :core.

- Add grpc protos to support takeoffer, confirmpaymentsent, confirmpaymentreceived

	Only takeoffer is implemented in this commit.

- Refactor OfferInfo grpc proto wrapper, and add offer state field

- Add new TradeInfo grpc proto wrapper

- Implement takeoffer on server and cli side

- Refactor offer/trade tests, add test cases

- Implement confirmpaymentsent on server and cli side

- Enable confirmpaymentsent method tests

- Implement confirmpaymentsent on server and cli side

- Enable confirmpaymentreceived method tests

Resolves issue found during bisq-network#4672
review, and mentioned in comment
bisq-network#4672 (comment)

Resolves issue found during bisq-network#4673
review, and mentioned in comment
bisq-network#4673 (comment)

Resolves issue found during bisq-network#4673
review, and suggested in comment
bisq-network#4673 (comment)

Resolves issue found during bisq-network#4673
review, and suggested in comment
bisq-network#4673 (comment)

Also shortened comment lines to < 90 chars.

Resolves issue found during bisq-network#4673
review, and suggested in comment
bisq-network#4673 (comment)