CollectionView migration

[mpbw2]

Continuation of #934 (new PR due to age of 934 resulting in a lot of diff noise). Screenshots below show Before (L) & After (R) for iOS & Android. Almost pixel perfect but struggling in some areas, possibly due to changes in dip calculations under the hood.

@cscharf I've been defeated by the same NPE you ran into regarding the menu button within the grid item. Everything I've read about BindingContext tells me the Cipher should be accessible so something (probably obvious) is still afoot.

System.NullReferenceException: Object reference not set to an instance of an object

  at Bit.App.Utilities.AppHelpers.CipherListOptions (Xamarin.Forms.ContentPage page, Bit.Core.Models.View.CipherView cipher) [0x000c6] in /Users/matt/Documents/Work/Companies/Bitwarden/Repos/mobile/src/App/Utilities/AppHelpers.cs:24 

  at Bit.App.Pages.GroupingsPageViewModel.CipherOptionsAsync (Bit.Core.Models.View.CipherView cipher) [0x0004b] in /Users/matt/Documents/Work/Companies/Bitwarden/Repos/mobile/src/App/Pages/Vault/GroupingsPage/GroupingsPageViewModel.cs:517 

[cscharf]

Looks good, will follow up on the issue you're seeing there, maybe with a fresh head now I'll be of some use there, 😉

[cscharf]

Are these encoded correctly? Just want to ensure the character is still valid/good. IMO would be more clear to use the unicode char code w/ escape character here explicitly defined, or hex representation of that char code, vs. the actual embedded unicode character (which depending on your editor is pretty hard to decipher/check).

[cscharf]

@mportune-bw , I notice that in RowSelected for GroupingsPage it checks the following:

if (!(e.SelectedItem is GroupingsPageListItem item))
{
    return;
}

I wonder if that has anything to do with the null exception you're getting when referencing the GroupingsPageListItem in that CipherOptionsAsync(CipherView cipher) method that's being called in the button command for that menu. Feels like I'm stretching it, like perhaps the command is being fired the first time with null and then it blows up, but perhaps it would be called twice if the first time just ignored the call and return; early.

[mpbw2]

@cscharf No dice unfortunately, however this leads me to look at something else possibly connected, so thanks!

[mpbw2]

Replaced with #1374