Improve Should-BeString assertion

[nohwnd]

Checklist

• Feature request has a meaningful title
• I have searched the existing issues. See all issues
• I have tested using the latest version of Pester. See Installation and update guide.

Summary of the feature request

• Improve should be string assertion to show difference in string, by the same arrow marker as Should -Be
• To show the text with whitespace even when using non-whitespace mode (by going over the string ourselves).

How should it work?

No response