Edge TB: Expose WebApps APIs, Fixes AB#3409879

[melissaahn]

Summary:

In this PR, we:

• Expose the WebApp APIs via BrokerMsalController. OneAuth is already using this class to call similar Edge APIs.
  • getSupportedWebAppContracts(String minBrokerProtocolVersion): this method is called by OneAuth to make sure that the broker can handle the request.
  • executeWebAppRequest(String Request, String minBrokerProtocolVersion): this method handles requests for GetToken, GetCookies, and SignOut.
• Implement the bundle helper methods for creating the bundle and extracting the results from the result bundle.
• Adds the bundle keys to AuthenticationConstants, where both common and broker can access them.

Related broker PR: https://github.com/AzureAD/ad-accounts-for-android/pull/3256

AB#3409879

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[Copilot]

Pull Request Overview

This PR introduces support for WebApps APIs in the Edge Token Broker by adding two new broker operations: getSupportedWebAppContracts and executeWebAppRequest. These operations enable the broker to expose WebApps functionality through the existing broker protocol infrastructure.

Key Changes

• Added new broker protocol constants for WebApps API communication (request/response/error keys)
• Implemented two new broker operations in BrokerMsalController for getting supported contracts and executing web app requests
• Added corresponding adapter methods for bundling requests and extracting results from broker responses

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
AuthenticationConstants.java	Defines new broker protocol constants for WebApps API keys (contracts, request, response, error)
MsalBrokerRequestAdapter.java	Adds methods to construct request bundles for getSupportedWebAppContracts and executeWebAppRequest operations
MsalBrokerResultAdapter.java	Implements result extraction methods for WebApps operations with null-safety checks
BrokerMsalController.java	Implements the two main WebApps broker operations following the existing broker operation pattern

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