Android: Basic support configuration changes

[emmauss]

What does the pull request do?

This add basic support for configuration changes, enough to prevent recreating the main activities when such changes occur, such as rotating the device. Only orientation change and resizing are handled.
Also, removes the view from logical tree when the activity is destroyed due to an unhandled configuration change, or by the os due to resource constraints. When the activity is recreated, the view is restored from the viewmodel. There is a rendering bug that occurs after recreating the activity, when the screen is black, and updates to the scene will only make it show the background with outlines of some controls, This requires further investigation.

What is the current behavior?

Currently, rotating the device will cause the activity to be recreated, which causes the bug noted above.

What is the updated/expected behavior with this PR?

Rotating the device will only update the size of the main view

How was the solution implemented (if it's not obvious)?

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/Documentation with user documentation

Fixed issues

[emmauss]

To support viewmodel and proper lifecycle management, the main activity now derives from AppCompatActivity. This made the ResourceDesigner.cs file to grow quite large.

[avaloniaui-team]

You can test this PR using the following package version. 0.10.999-cibuild0018205-beta. (feed url: https://nuget.avaloniaui.net/repository/avalonia-all/index.json) [PRBUILDID]

[maxkatz6]

Note that xamarin sdk will be replaced soon
#6922

[emmauss]

Note that xamarin sdk will be replaced soon #6922

Ok, that would make it much easier to build on linux.

[avaloniaui-team]

You can test this PR using the following package version. 0.10.999-cibuild0018216-beta. (feed url: https://nuget.avaloniaui.net/repository/avalonia-all/index.json) [PRBUILDID]

[emmauss]

Note that xamarin sdk will be replaced soon #6922

What's the status on that PR and it's dependency? Will they be merged soon?

[maxkatz6]

@emmauss #6922 PR is blocked by #7347, which is blocked by #5831. We plan to have all of these changes for next major release.
But I think this PR can be merged before that, I will need to adjust my 6922 PR after.
Although I am not really experienced with Xamarin SDK, and if you want, you can rebase this PR on top of 6922. If you have free time for it.

[emmauss]

@emmauss #6922 PR is blocked by #7347, which is blocked by #5831. We plan to have all of these changes for next major release. But I think this PR can be merged before that, I will need to adjust my 6922 PR after. Although I am not really experienced with Xamarin SDK, and if you want, you can rebase this PR on top of 6922. If you have free time for it.

I'll rebase over your PR as the Xamarin SDK has a few thing that makes working with it harder, compared to the dotnet sdk. Also, the dotnet sdk added support for android on linux on the preview

[emmauss]

rebased over #6922 .

[avaloniaui-team]

You can test this PR using the following package version. 0.10.999-cibuild0018760-beta. (feed url: https://nuget.avaloniaui.net/repository/avalonia-all/index.json) [PRBUILDID]

[emmauss]

PR ready for review

[avaloniaui-team]

You can test this PR using the following package version. 0.10.999-cibuild0018781-beta. (feed url: https://nuget.avaloniaui.net/repository/avalonia-all/index.json) [PRBUILDID]