update abi-gen with new method interfaces (#2325)

* update abi-gen with new method interfaces

* wip: get all packages to build

* wip: get all packages to build

* Fix two contract wrapper calls

* Export necessary types part of the contract wrapper public interfaces

* Revive and fix wrapper_unit_tests

* Remove duplicate type

* Fix lib_exchange_rich_error_decoder tests

* Fix remaining test failures in contracts-* packages

* Prettier fixes

* remove transactionHelper

* lint and update changelogs

* Fix prettier

* Revert changes to reference docs

* Add back changelog already published and add revert changelog entry

* Add missing CHANGELOG entries

* Add missing comma

* Update mesh-rpc-client dep

* Update Mesh RPC logic in @0x/orderbook to v6.0.1-beta

* Align package versions

packages/0x.js/src/index.ts

@@ -41,6 +41,15 @@ export {
     ExchangeTransactionExecutionEventArgs,
 } from '@0x/abi-gen-wrappers';
 
+export {
+    ContractEvent,
+    SendTransactionOpts,
+    AwaitTransactionSuccessOpts,
+    ContractFunctionObj,
+    ContractTxFunctionObj,
+    SubscriptionErrors,
+} from '@0x/base-contract';
+
 export import Web3ProviderEngine = require('web3-provider-engine');
 
 export {
@@ -76,8 +85,6 @@ export {
     SimpleEvmOutput,
     SimpleEvmBytecodeOutput,
     EIP712DomainWithDefaultSchema,
-    AwaitTransactionSuccessOpts,
-    SendTransactionOpts,
     EventCallback,
     IndexedFilterValues,
     DecodedLogEvent,