feat: update styles to WinUI 2

[soumyamahunt]

This PR fixes conflicts in #806. With WCT moving to WinUI 2.5 it is essential Notepads should update to WinUI 2.5 to maintain compatibility. Most of the designs have been updated to implement rounded corners etc.

PR Type

What kind of change does this PR introduce?

• Feature

[soumyamahunt]

@Jasonstein there is a bug I noticed in WinUI2 which have been reported here we can either wait for it to be fixed or update our styles for different behavior. Most of the work is done, I just have following queries to finish the transition:

1. Do you still want to host parts of WCT in project itself, do you want to remove those parts??
2. Do you want to move from Notepads' custom SetsView to WinUI's TabView or keep things as it is??
3. Have a look on different control styles and let me know if you want me to change anything.

[0x7c13]

@Jasonstein there is a bug I noticed in WinUI2 which have been reported here we can either wait for it to be fixed or update our styles for different behavior. Most of the work is done, I just have following queries to finish the transition:

1. Do you still want to host parts of WCT in project itself, do you want to remove those parts??
2. Do you want to move from Notepads' custom SetsView to WinUI's TabView or keep things as it is??
3. Have a look on different control styles and let me know if you want me to change anything.

1. As long as they matches the design.
2. No, I don't like the look and feel of their approach. At least it does not fit well in Notepads.
3. I like the current approach as it is.

[soumyamahunt]

@Jasonstein here are comparison some of the design changes:

Before	After

[0x7c13]

Overall looks good to me. There is only one thing that makes me sad: most of the current Windows apps are still using rectangle design and also the app Window itself is a rectangle and it does not fit well with the overall rounded corners of the controls. Maybe we should do it later once Windows is fully embracing the rounded corner design and I believe it should be coming real soon. Is there any way to keep all your existing work as it is but set the corner radius to 0 and makes it look just like before? And when time is right, we can set it to rounded corner if that's doable.

[soumyamahunt]

Overall looks good to me. There is only one thing that makes me sad: most of the current Windows apps are still using rectangle design and also the app Window itself is a rectangle and it does not fit well with the overall rounded corners of the controls. Maybe we should do it later once Windows is fully embracing the rounded corner design and I believe it should be coming real soon. Is there any way to keep all your existing work as it is but set the corner radius to 0 and makes it look just like before? And when time is right, we can set it to rounded corner if that's doable.

I have disabled rounded corners for now and added notes to reenable them once SunValley becomes GA.

Also, are you satisfied with the WinUI's Colorpicker or do you want to use the Community Toolkit's Colorpicker??

Regarding the WinUI's TabView, we can customize the look and feel similar to Notepads while not maintaining the code. Do you still want to use current SetsView??