Fix default file inclusion of .RESW and image files in .NET projects

[rohanp-msft]

The existing solution (added in #771) has an issue: app devs cannot opt out an image or a RESW file from PRI inclusion.

Closes #980

How verified (commit 11)

Setup:

1. Uninstall the existing VSIX.
2. Install WindowsAppSDK.Extension.Experimental.vsix from the output of the build pipeline run.
3. Create a new app using the "WinUI.Desktop.Cs.PackagedApp" template.
4. Install Microsoft.WindowsAppRuntime.1.0.msix manually.

Verification:
(BA below means Build Action)

1. Copy paste a RESW file, a .PNG file, and a .JPG file into the folder containing the .CSPROJ file. Build and run. Examine PRI. Examine bin placing.
2. Opt-out the RESW file and the PNG file. Build and run. Examine PRI. Examine bin placing.
3. Opt-in the files that were opted out. Build and run. Examine PRI. Examine bin placing.
4. Restart VS. Rebuild and run. Examine PRI.
5. Opt-out files. Restart VS. Build. Examine PRI.
6. Set EnableDefaultPRIResourceItems to false. BA of RESW file changed to None. Remove set. BA changes back to PRIResource.
7. Set EnableDefaultContentItems to false. BA of image file changed to None. Remove set. BA changes back to Content. (BA of image file that was None already remains None and is None after set is removed too.)
8. Set EnableDefaultItems to false. All image and RESW files disappeared in Solution Explorer (regardless of their BA). Remove set. All files come back.

Note:

• Issue 1: There is an issue I found for which I'll create a tracking item and link to this PR:
  • Let's say you create a new app. You build and run it. That generates a resources.pri.
  • You then copy-paste some resource files into the project folder. The Build Action of these files will be set correctly by default (which is the point of the change).
  • You then hit F5.
  • The resources.pri in the build output after the F5 Run doesn't have the new resources. I suspect the PRI is not regenerated.
  • If the app is rebuilt, then the PRI's contents are correct.
• Issue 2: This solution does not work for resource files that are added from outside the project folder. For them, manual action is needed to set the Build Action to PRIResource or Content. I'll create a tracking item for this too and link to this PR.

[huichen123]

[rainersigwald]

I want to be sure that things like the introduction of EnableDefaultPRIResourceItems is not unacceptable

I think this is a very reasonable extension of the current pattern. With MSBuild there's always a risk of name collision but this is very specific and doesn't appear to be currently used.

@dsplaisted do you have any concerns from the SDK perspective?

[dsplaisted]

The globbing looks good, but it seems like there may be issues with moving the EnableCoreMrtTooling logic to .props files.

A possible way to work around this would be to move the logic that sets EnableCoreMrtTooling back to the .targets, import MrtCore.props unconditionally, and then add a check for EnableCoreMrtTooling to all the ItemGroups in MrtCore.props.

[rohanp-msft]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).