Consolidate Solution Files

[TheCodeTraveler]

Description

Similar PR for CommunityToolkit.Maui.Markup: CommunityToolkit/Maui.Markup#10

This removes duplicate global.json or Directory.Build.props files, preventing a future error where one global.json or Directory.Build.props files may be updated.

Prior to this PR, both CommunityToolkit.Maui.sln and CommunityToolkit.Maui.Sample.sln used separate files for global.json or Directory.Build.props, however, both files contained the sample implementations.

Detailed Solution

• Move global.json to root folder
• Move Directory.Build.props to root folder
• Update file reference paths in CommunityToolkit.Maui.sln
• Update file reference paths in CommunityToolkit.Maui.Samples.sln
• Adds dotnet_diagnostic.CS4014.severity = error to .editorconfig
  • Ported from Xamarin.CommunityToolkit's .editorconfig
  • Ensures each Task is await'd, avoiding async/await bugs in future PRs