Add the cloudSetting option for ARM Modular SDK

[MaryGao]

fixes #3188

This PR adds multi-cloud support for MPG, enabling generated clients to connect to different Azure cloud environments.

Changes made:

• Added AzureClouds fixed enum with values for different cloud environments (Public, China, US Government)
• Updated the client generator to accept an cloudSetting parameter in client options
• Modified endpoint setup logic to use the cloud parameter when determining the endpoint URL

Now users can specify which Azure cloud environment to connect to when creating a client:

import { NetworkCloud, AzureClouds } from "@azure/arm-networkcloud";
import { DefaultAzureCredential } from "@azure/identity";

// Create a client for the Azure China Cloud environment
const client = new NetworkCloud(
  new DefaultAzureCredential(),
  "your-subscription-id",
  { 
    cloudSetting: AzureClouds.AzureChinaCloud 
  }
);

[xiangyan99]

LGTM

[Copilot]

Pull Request Overview

This PR adds multi-cloud support for Azure ARM Modular SDK clients, enabling them to connect to different Azure cloud environments (Public, China, US Government). The implementation includes a new AzureClouds enum and cloud-specific endpoint resolution logic.

Key changes:

• Added AzureClouds enum with predefined cloud environment values and endpoint mapping function
• Updated client options interface to include optional cloudSetting parameter for ARM clients
• Modified endpoint resolution logic to use cloud-specific endpoints when cloudSetting is provided

Reviewed Changes

Copilot reviewed 8 out of 32 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/typespec-ts/static/static-helpers/cloudSettingHelpers.ts	New helper file defining AzureClouds enum and getArmEndpoint function for cloud endpoint resolution
packages/typespec-ts/src/modular/static-helpers-metadata.ts	Added metadata definitions for cloud setting helpers
packages/typespec-ts/src/modular/helpers/clientHelpers.ts	Updated endpoint parameter building to support cloud setting fallback for ARM clients
packages/typespec-ts/src/modular/buildRootIndex.ts	Added export logic for AzureClouds enum and refactored export helper functions
packages/typespec-ts/src/modular/buildClientContext.ts	Added cloudSetting property to ARM client options and parameter name conflict detection
packages/typespec-ts/src/lib.ts	Added new diagnostic for parameter name conflicts
packages/typespec-ts/src/index.ts	Registered CloudSettingHelpers in the static helpers collection
packages/typespec-ts/src/framework/load-static-helpers.ts	Extended framework to support enum declarations in static helpers

[xirzec]

Small comments on the generated code, only one that I feel strongly about is fixing the error message.