Fix for the navigation to the SelectAllText page on macOS

[vhugogarcia]

Description of Change

Updated the StaticResource set for the border, since it was preventing to navigate to the SelectAllText page on macOS only. It works on iOS, Android, and Windows as well.

The documentation has been created on the following PR: MicrosoftDocs/CommunityToolkit#316

Linked Issues

• Fixes #432

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: Created the Select All Text Behavior documentation MicrosoftDocs/CommunityToolkit#316

cc: @pictos @brminnick

[VladislavAntonyuk]

Approve, just make sure we renamed it in the whole project SoftFrameBackgroundColor

[brminnick]

Thanks @vhugogarcia! Approved

I don't see SoftFrameBackgroundColor used anywhere in the app. It was likely a legacy resource we ported from XamarinCommunityToolkit.