Add sovereign cloud support to AzureCloudInstance enum

[Copilot]

Changes proposed in this request

PR #5671 added instance discovery support for Bleu (France), Delos (Germany), and GovSG (Singapore) sovereign clouds, but the AzureCloudInstance enum was not updated to expose them.

This PR adds:

• Three new enum values: AzureBleu, AzureDelos, AzureGovSG
• URL mappings in AuthorityInfo.GetCloudUrl() for the new clouds
• Test coverage for all authority audience combinations

Developers can now use the enum instead of hardcoding URLs:

// Before: had to use custom authority URL
var app = PublicClientApplicationBuilder.Create(clientId)
    .WithAuthority("https://login.sovcloud-identity.fr/tenantId/")
    .Build();

// After: use the enum
var app = PublicClientApplicationBuilder.Create(clientId)
    .WithAuthority(AzureCloudInstance.AzureBleu, tenantId)
    .Build();

Testing

Added 9 test cases covering all three new clouds with AzureAdMultipleOrgs, AzureAdAndPersonalMicrosoftAccount, and PersonalMicrosoftAccount audiences.

Performance impact

None. Changes are additive enum values and switch cases.

Documentation

• All relevant documentation is updated.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Documentation] Sovereign cloud usage examples and AzureCloudInstance enum</issue_title>
<issue_description>Documentation related to component
Authentication to sovereign clouds

Please check those that apply

• typo
• documentation doesn't exist
• documentation needs clarification
• error(s) in example
• needs example

Description of the issue
In PR #5671, support for sovereign clouds (Bleu, Delos, GovSG) has been added to MSAL.Net.

It would be great to have a usage example on how to authenticate against these clouds.

I would also like to see how the Microsoft.Identity.Client.AzureCloudInstance enum is connected to this, as the enum does not yet contain any hint to the new sovereig clouds.
</issue_description>

<agent_instructions>Update the AzureCloudInstance enum</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Documentation] Sovereign cloud usage examples and AzureCloudInstance enum #5706

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[Copilot]

Pull request overview

This PR exposes newly supported sovereign clouds (Bleu/France, Delos/Germany, GovSG/Singapore) through the public AzureCloudInstance enum and wires them into authority host resolution, with unit tests validating authority construction for common AAD audiences.

Changes:

• Add AzureBleu, AzureDelos, and AzureGovSG to AzureCloudInstance.
• Map the new enum values to their login hosts in AuthorityInfo.GetCloudUrl().
• Extend PublicClientApplicationBuilderTests to cover the new clouds across multiple authority audiences.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tests/Microsoft.Identity.Test.Unit/AppConfigTests/PublicClientApplicationBuilderTests.cs	Adds authority-construction test cases for the three new clouds across multiple audiences.
src/client/Microsoft.Identity.Client/AppConfig/AzureCloud.cs	Extends the public AzureCloudInstance enum with three sovereign cloud values.
src/client/Microsoft.Identity.Client/AppConfig/AuthorityInfo.cs	Adds URL mappings for the new enum values used when constructing AAD authorities.

[Copilot]

These new enum members are a public API surface change. The repo uses PublicApiAnalyzers with per-TFM API baselines; please add the new AzureCloudInstance members (AzureBleu=5, AzureDelos=6, AzureGovSG=7) to the corresponding src/client/Microsoft.Identity.Client/PublicApi/<tfm>/PublicAPI.Unshipped.txt files (or move to Shipped if appropriate), otherwise the public API analyzer will fail the build.

Suggested change

	AzureBleu,
	/// <summary>
	/// Azure Delos sovereign cloud (Germany). Maps to https://login.sovcloud-identity.de
	/// </summary>
	AzureDelos,
	/// <summary>
	/// Azure GovSG sovereign cloud (Singapore). Maps to https://login.sovcloud-identity.sg
	/// </summary>
	AzureGovSG,
	AzureBleu = 5,
	/// <summary>
	/// Azure Delos sovereign cloud (Germany). Maps to https://login.sovcloud-identity.de
	/// </summary>
	AzureDelos = 6,
	/// <summary>
	/// Azure GovSG sovereign cloud (Singapore). Maps to https://login.sovcloud-identity.sg
	/// </summary>
	AzureGovSG = 7,