Feature/liquidity provider sandbox (#16)

* Update liquidity provider feature to use sandbox

* add support for liquidity provider feature in the exchange proxy swap quote consumer

* Move to off-chain liquidity provider registry

* Update ILiquidityProvider interface

* Remove some unused artifacts and wrappers

* Consolidate ILiquidityProvider

* prettier

* lint

* Address PR feedback

* Add failover to sandbox

* Add test for failover behavior in LiquidityProviderSandbox

* Update changelogs

* Emit events for the new LiquidityProvider scenarios

* Fix swap quote consumer bug

* post-rebase fixes

* `@0x/contracts-zero-ex`: bump feature versions

* Add default field to TokenAdjacencyGraph

* update addresses

Co-authored-by: Lawrence Forman <me@merklejerk.com>

packages/migrations/CHANGELOG.json

@@ -1,4 +1,13 @@
 [
+    {
+        "version": "6.5.0",
+        "changes": [
+            {
+                "note": "Add `exchangeProxyLiquidityProviderSandbox` address",
+                "pr": 16
+            }
+        ]
+    },
     {
         "timestamp": 1604385937,
         "version": "6.4.7",

packages/migrations/src/migration.ts

@@ -402,6 +402,7 @@ export async function runMigrationsAsync(
         exchangeProxyAllowanceTarget: exchangeProxyAllowanceTargetAddress,
         exchangeProxyTransformerDeployer: txDefaults.from,
         exchangeProxyFlashWallet: exchangeProxyFlashWalletAddress,
+        exchangeProxyLiquidityProviderSandbox: NULL_ADDRESS,
         transformers: {
             wethTransformer: wethTransformer.address,
             payTakerTransformer: payTakerTransformer.address,