[release/10.0.1xx] Improve templates for GA

[mattleibow]

Backport of #32251 to release/10.0.1xx

[Copilot]

Pull Request Overview

This PR re-enables previously commented-out template tests for the --sample-content option and addresses related template issues. The changes resolve integration test failures by updating warning suppressions and adding missing package dependencies.

Key changes:

• Re-enables two --sample-content test cases that were previously disabled due to issue #32151
• Updates warning suppression from XC0103 to NU1608 to match current CommunityToolkit.Maui issues
• Fixes indentation inconsistencies in the template's MauiProgram.cs
• Adds explicit Microsoft.Maui.Essentials package reference to the project template

Reviewed Changes

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

File	Description
src/TestUtils/src/Microsoft.Maui.IntegrationTests/SimpleTemplateTest.cs	Re-enables two test cases for --sample-content option that were previously commented out
src/Templates/src/templates/maui-mobile/MauiProgram.cs	Fixes indentation (tabs vs spaces) and fully qualifies ContentPanel type namespace
src/Templates/src/templates/maui-mobile/MauiApp.1.csproj	Updates warning suppression from XC0103 to NU1608 and adds explicit Microsoft.Maui.Essentials package reference

Comments suppressed due to low confidence (1)

src/TestUtils/src/Microsoft.Maui.IntegrationTests/SimpleTemplateTest.cs:49

• The warning code and issue reference are now inconsistent with the project template. The template was updated to suppress NU1608 with reference to issue #2921, but the test still references XC0103 and issue #2205. These should be synchronized to reflect the current warning suppression approach.

				"XC0103", // https://github.com/CommunityToolkit/Maui/issues/2205

[Copilot]

Adding an explicit reference to Microsoft.Maui.Essentials may be unnecessary as it's typically included transitively through Microsoft.Maui.Controls. This could create maintenance overhead if the transitive dependency relationship changes in future versions. Verify if this explicit reference is truly required or if it's being added to work around a specific issue that should be documented.

Suggested change

<PackageReference Include="Microsoft.Maui.Essentials" Version="$(MauiVersion)" />