chore: Add package icon to the IgniteUI.Blazor.GridLite NuGet package

[jsakamotoIGJP]

Description

Add a package icon to the IgniteUI.Blazor.GridLite NuGet package. src/IgniteUI.Blazor.GridLite/nupkg-icon.png is added, and PackageIcon in IgniteUI.Blazor.GridLite.csproj points to it.

Motivation / Context

The package has no icon today. See #76.

Type of Change (check all that apply):

• Bug fix
• New functionality
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (no functional changes)
• Documentation
• Demos
• CI/CD
• Tests
• Changelog

Component(s) / Area(s) Affected:

NuGet packaging

How Has This Been Tested?

• Unit tests
• Manual testing
• Automated e2e tests

I ran npm ci, npm run build and dotnet build -c Release for the library project. The generated nupkg contains nupkg-icon.png, and the nuspec has <icon>nupkg-icon.png</icon>.

Test Configuration:

• .NET version: .NET SDK 10.0.401
• Hosting model: Not applicable
• Browser(s): Not applicable
• OS: Windows 11

Screenshots / Recordings

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code
• This PR includes API docs for newly added methods/properties
• This PR includes CHANGELOG.md updates for newly added functionality
• This PR contains breaking changes
• Accessibility (ARIA, keyboard navigation, focus management) has been verified

Closes #76