feat: add multichain_ux flag (#7122)

* feat: add multichain_ux flag

* update flag text

* add new flag file

src/components/FeatureFlagModal/FeatureFlagModal.tsx

 import { BaseVariant, FeatureFlag, featureFlagSettings, useUpdateFlag } from 'featureFlags'
 import { useBaseEnabledFlag } from 'featureFlags/flags/baseEnabled'
 import { useForceUniswapXOnFlag } from 'featureFlags/flags/forceUniswapXOn'
+import { useMultichainUXFlag } from 'featureFlags/flags/multichainUx'
 import { useRoutingAPIForPriceFlag } from 'featureFlags/flags/priceRoutingApi'
 import { TraceJsonRpcVariant, useTraceJsonRpcFlag } from 'featureFlags/flags/traceJsonRpc'
 import { UniswapXVariant, useUniswapXFlag } from 'featureFlags/flags/uniswapx'
@@ -242,6 +243,12 @@ export default function FeatureFlagModal() {
         featureFlag={FeatureFlag.baseEnabled}
         label="Enable Base"
       />
+      <FeatureFlagOption
+        variant={BaseVariant}
+        value={useMultichainUXFlag()}
+        featureFlag={FeatureFlag.multichainUX}
+        label="Updated Multichain UX"
+      />
       <FeatureFlagGroup name="Debug">
         <FeatureFlagOption
           variant={TraceJsonRpcVariant}

src/featureFlags/flags/multichainUx.ts

+import { BaseVariant, FeatureFlag, useBaseFlag } from '../index'
+
+export function useMultichainUXFlag(): BaseVariant {
+  return useBaseFlag(FeatureFlag.multichainUX)
+}

src/featureFlags/index.tsx

@@ -16,6 +16,7 @@ export enum FeatureFlag {
   forceUniswapXOn = 'uniswapx_force_on', // forces routing-api's feature flag for uniswapx to turn on as well
   uniswapXEthOutputEnabled = 'uniswapx_eth_output_enabled',
   baseEnabled = 'base_enabled',
+  multichainUX = 'multichain_ux',
 }
 
 interface FeatureFlagsContextType {