chore: add isGaslessSwapEnabled swap feature flag (#6573)

## Explanation

Adds the isGaslessSwapEnabled to the feature flag schema so
`selectBridgeFeatureFlags` can return the value to clients

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## References

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Fixes https://consensyssoftware.atlassian.net/browse/SWAPS-2937

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [x] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [x] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

Author: micaelae

packages/bridge-controller/CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - **BREAKING:** Bump peer dependency `@metamask/assets-controller` from `^74.0.0` to `^75.0.0` ([#6570](https://github.com/MetaMask/core/pull/6570))
 - Bump `@metamask/keyring-api` from `^20.1.0` to `^21.0.0` ([#6560](https://github.com/MetaMask/core/pull/6560))
+- Add optional `isGaslessSwapEnabled` LaunchDarkly config to feature flags schema ([#6573](https://github.com/MetaMask/core/pull/6573))
 - Bump `@metamask/utils` from `^11.4.2` to `^11.8.0` ([#6588](https://github.com/MetaMask/core/pull/6588))
 
 ## [42.0.0]

packages/bridge-controller/src/utils/validators.test.ts

@@ -6,12 +6,20 @@ describe('validators', () => {
       {
         response: {
           chains: {
-            '1': { isActiveDest: true, isActiveSrc: true },
+            '1': {
+              isActiveDest: true,
+              isActiveSrc: true,
+              isGaslessSwapEnabled: true,
+            },
             '10': { isActiveDest: true, isActiveSrc: true },
             '137': { isActiveDest: true, isActiveSrc: true },
             '324': { isActiveDest: true, isActiveSrc: true },
             '42161': { isActiveDest: true, isActiveSrc: true },
-            '43114': { isActiveDest: true, isActiveSrc: true },
+            '43114': {
+              isActiveDest: true,
+              isActiveSrc: true,
+              isGaslessSwapEnabled: false,
+            },
             '56': { isActiveDest: true, isActiveSrc: true },
             '59144': { isActiveDest: true, isActiveSrc: true },
             '8453': { isActiveDest: true, isActiveSrc: true },

packages/bridge-controller/src/utils/validators.ts

@@ -87,6 +87,7 @@ export const ChainConfigurationSchema = type({
   topAssets: optional(array(string())),
   isUnifiedUIEnabled: optional(boolean()),
   isSingleSwapBridgeButtonEnabled: optional(boolean()),
+  isGaslessSwapEnabled: optional(boolean()),
 });
 
 export const PriceImpactThresholdSchema = type({