feat: Enhance the no search result state

[Zakaria Tahri (Zakariathr22)]

Description

Improved the empty state shown when no samples match the search query.

• Displays the search query.
• Provides search tips and examples.
• Adds a View all samples button.
• Improves the overall empty-state design.
• Uses the same illustration as the Outlook application, with some colors adjusted to better fit WinUI Gallery :-)
  https://res.public.onecdn.static.microsoft/assets/mail/illustrations/emptySpotlight/v2/dark.svg

Motivation and Context

• Previously, no results only displayed "No results match your search."
• This update provides better UI/UX, useful guidance and an easy way to return to all samples.

How Has This Been Tested?

Manually tested

Screenshots (if appropriate):

Before

After

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)