Fix TokenizingTextBox header to behave like normal text control headers

[marcelwgn]

Fixes #4096

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

Header rendered inside the TokenizingTextBox

What is the new behavior?

Header now renders above the TokenizingTextBox input area.

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Pull Request has been submitted to the documentation repository instructions. Link:
• Sample in sample app has been added / updated (for bug fixes / features)
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• New major technical changes in the toolkit have or will be added to the Wiki e.g. build changes, source generators, testing infrastructure, sample creation changes, etc...
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

Other information

Also took the liberty to add the properties for the header presenter that are also present for the TextBox header presenter.

[ghost]

Thanks chingucoding for opening a Pull Request! The reviewers will test the PR and highlight if there is any conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌

[michael-hawker]

Would we want Footer be also abstracted here? Otherwise it'll be in the TextBox part again, right?

[marcelwgn]

Funnily, in my testing, setting the footer does not actually change anything. So should we move the footer out of the ItemsControl like the header too?

[michael-hawker]

Yeah, I think while we're at it here, it makes sense. :)

[marcelwgn]

Done!

[Rosuavio]

@michael-hawker I see that this was removed from the Bugs7.1 board, but the related issue is on that board, is there are reason that this PR is not on the board?

[michael-hawker]

@RosarioPulella we only put PRs on the board that have no corresponding issue. If there's an issue for the PR, then the issue is what stays on the board. If we have both a PR and an issue on the board the board gets cluttered with duplicates. 🙂

That's why we also set the milestone, as the PR is still in the 7.1 milestone to match too.

[michael-hawker]

Thanks @chingucoding for fixing this! 🎉🎉🎉