[5.2] Add new trusted AKV URLs for FR and DE

[paulmedynski]

Port of #3482 from main to release/5.2

• Added 4 new trusted AKV URLs.
• Fixed existing manual tests and added unit tests.
• Addressed incompatible .NET syntax that isn't supported by C# 9.0.

[Copilot]

Pull Request Overview

This PR adds support for new trusted Azure Key Vault (AKV) URLs for France and Germany sovereign clouds, specifically adding 4 new trusted endpoints for both regular vaults and managed HSM vaults. The changes address compatibility with .NET 6.0 syntax requirements and improve test coverage.

• Adds 4 new trusted AKV URLs for France (sovcloud-api.fr) and Germany (sovcloud-api.de) sovereign clouds
• Refactors existing manual tests to use shared error message generation logic
• Adds comprehensive unit tests for URL validation including both valid and invalid scenarios

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
Constants.cs	Adds 4 new trusted AKV domain names and improves code formatting/documentation
Utils.cs	Changes return type from Exception to ArgumentException for consistency
TrustedUrlsTest.cs	New comprehensive test file covering URL validation scenarios
ExceptionTestAKVStore.cs	Refactored to use shared error message generation from TrustedUrlsTest
Microsoft.Data.SqlClient.ManualTesting.Tests.csproj	Adds new test file and reorganizes existing test file references

Comments suppressed due to low confidence (2)

src/Microsoft.Data.SqlClient/tests/ManualTests/AlwaysEncrypted/TrustedUrlsTest.cs:23

• The variable name 'clazz' should be renamed to 'type' or 'providerType' to better reflect its purpose and follow C# naming conventions.

            var clazz = assembly.GetType("Microsoft.Data.SqlClient.AlwaysEncrypted.AzureKeyVaultProvider.SqlColumnEncryptionAzureKeyVaultProvider");

src/Microsoft.Data.SqlClient/tests/ManualTests/AlwaysEncrypted/TrustedUrlsTest.cs:24

• Using 'clazz' here is inconsistent with C# naming conventions. Consider using 'type' or 'providerType' for better readability.

            _method = clazz.GetMethod(