Clicking the currently selected item in a navigation view when ``SelectionFollowsFocus`` is enabled causes an odd animation

Describe the bug

When SelectionFollowsFocus is enabled in a muxc navigation view, clicking the currently selected item will cause the selection animation to start from the beginning then move back to the selected item.

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Open XCG
2. Navigate to NavigationView page
3. Scroll down to “tying selection and focus” section
4. Click any item, then click it again
5. Weird animation

Expected behavior

No animation should be shown, as the selection is not changed.

Screenshots

https://user-images.githubusercontent.com/59544401/125229048-c7c6f080-e28a-11eb-8ee7-a35ae5cb092d.mp4

Version Info

NuGet package version: [Microsoft.UI.Xaml 2.6.0]

Windows app type:

UWP	Win32
Yes

Windows 10 version	Saw the problem?
Insider Build (22000.65)	Yes
October 2020 Update (19042)	Yes
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context Originally from https://github.com/files-community/Files/issues/5387

[winston-de]

This looks like an issue in the sample. I don’t repro this in other navview items. We should no-op if we are already on the same page.

I can repro this issue in other apps as well, I was just using xaml controls gallery as a convenient example of how to repro this.

https://user-images.githubusercontent.com/59544401/126079691-fca8675b-668a-471b-9ff1-65741ccc638a.mp4

[gregwoo-microsoft]

Based on the comments above, I’ll transfer this back to the WinUI repo.