BalancerBridge (#2613)

* Add BalancerBridge and Sampler functions

* Update sampler artifacts/wrappers

* Add Balancer support to AssetSwapper + related refactoring

* Make use of GraphQL instead of sampler

* "fix" build and add mainnet BalancerBridge tests

* address some comments

* add balancer cache and fix DexSampler tests

* lint

* wip: tests for balancer sampler ops

* Fix market operation utils test

* balancer unit tests

* Return a buy quote of 0 if the buy amount exceeds the Balancer pool's balance

* Dynamic fee estimation

* Update contract addresses, export BalancerBridge wrapper

* Update changelogs

* Fix bugs discovered via simbot

* Fix issues in balancer_utils

* override `BigNumber.config` in configured_bignumber.ts

* Special case Balancer subops in  too

* Address some more comments

* Address Balancer performance issue

* Performance improvements

* Address comment

* Fix tests

Co-authored-by: xianny <xianny@gmail.com>

packages/tslint-config/tslint.json

@@ -65,7 +65,7 @@
         "no-lodash-isnull": true,
         "no-lodash-isundefined": true,
         "no-misused-new": true,
-        "no-non-null-assertion": true,
+        "no-non-null-assertion": false,
         "no-parameter-reassignment": true,
         "no-redundant-jsdoc": true,
         "no-return-await": true,