FOLDER grouping in default build target dropdown

[itzandroidtab]

This changes visible behavior

The following changes are proposed:

• Grouping default build targets dropdown based on CMake FOLDER property

The purpose of this change

When a project has a lot of targets it becomes a hassle to find the right default build target. In the project outline the targets are grouped. This PR also groups the default build target dropdown. Discussion #3949. When clicking on the folder it will show the corresponding targets.

Previous

New

After selecting the folder:

[itzandroidtab]

@gcampbell-msft @qarni What would I need to do to have this PR merged?

[gcampbell-msft]

@itzandroidtab Our apologies for the delay, we've been in the midst of the 1.19 official version release, so we've not been able to review community PR's. We hope to get to this soon, thanks and we appreciate your patience.

[gcampbell-msft]

@itzandroidtab First, please include a CHANGELOG.md entry.

Also, I like the idea of this PR and the screenshots you've provided look really good! I haven't taken a deeply close look at the code, but again it looks good.

HOWEVER, I think that this is probably a feature change that each user should be able to control if they would like. I think it'd be a great idea to add a setting that would allow people to choose whether they want this to be a flat list, or whether they want it to be structured using the FOLDER property. I could imagine a scenario where they only have a couple of targets, but if they're using the FOLDER property, even though there are only a limited set of options, they have to do multiple clicks to select it, due to the new implementation you've added.

I'd love to approve this feature, but I think it should have the added ability to control whether we use the flat list or the FOLDER grouping based on a setting. I currently don't have a strong opinion on whether the setting should default to the flat list or the FOLDER grouping.

@moyo1997 @itodirel @sinemakinci1 FYI, thoughts?