Add Popup.CloseAsync()

[brminnick]

Description of Change

This PR adds a new API to Popup: Task Popup.CloseAsync()

Linked Issues

• Fixes [Proposal] Add Popup.CloseAsync() #1222
• Fixes [BUG] Cannot open another popup shortly after closing the previous one on iOS. #1111
• Fixes [BUG] Repeatedly displaying and hiding the popup at short intervals does not display the Popup as intended on iOS. #1213

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: Add Popup.CloseAsync() MicrosoftDocs/CommunityToolkit#285

Additional information

[brminnick]

Hey @JoonghyunCho! We're seeing a Tizen error in the build. Could you take a look?
https://dev.azure.com/dotnet/CommunityToolkit/_build/results?buildId=94166&view=logs&j=67da6a11-18ef-5f70-9b43-fae7e6c83e18&t=49ed9970-d038-52c3-9405-25559677b293&l=575

C:\hostedtoolcache\windows\dotnet\packs\Samsung.Tizen.Sdk\7.0.114\targets\Samsung.Tizen.Sdk.Packaging.targets(161,5): error : The api-version specified in tizen-manifest file is 7. [D:\a\1\s\samples\CommunityToolkit.Maui.Sample\CommunityToolkit.Maui.Sample.csproj::TargetFramework=net7.0-tizen]
C:\hostedtoolcache\windows\dotnet\packs\Samsung.Tizen.Sdk\7.0.114\targets\Samsung.Tizen.Sdk.Packaging.targets(161,5): error : Current target framework net7.0-tizen is not supported in this api-version. [D:\a\1\s\samples\CommunityToolkit.Maui.Sample\CommunityToolkit.Maui.Sample.csproj::TargetFramework=net7.0-tizen]

[JoonghyunCho]

Hey @JoonghyunCho! We're seeing a Tizen error in the build. Could you take a look?

https://dev.azure.com/dotnet/CommunityToolkit/_build/results?buildId=94166&view=logs&j=67da6a11-18ef-5f70-9b43-fae7e6c83e18&t=49ed9970-d038-52c3-9405-25559677b293&l=575

C:\hostedtoolcache\windows\dotnet\packs\Samsung.Tizen.Sdk\7.0.114\targets\Samsung.Tizen.Sdk.Packaging.targets(161,5): error : The api-version specified in tizen-manifest file is 7. [D:\a\1\s\samples\CommunityToolkit.Maui.Sample\CommunityToolkit.Maui.Sample.csproj::TargetFramework=net7.0-tizen]

C:\hostedtoolcache\windows\dotnet\packs\Samsung.Tizen.Sdk\7.0.114\targets\Samsung.Tizen.Sdk.Packaging.targets(161,5): error : Current target framework net7.0-tizen is not supported in this api-version. [D:\a\1\s\samples\CommunityToolkit.Maui.Sample\CommunityToolkit.Maui.Sample.csproj::TargetFramework=net7.0-tizen]

Absolutely! Will take a look during the weekend or early next week :)

[pictos]

Just a small comment, but nothing that would block you from merging this puppy (:

[pictos]