Project-level default for await configuration

[Keith-McKinley]

Is your feature request related to a problem? Please describe.

It is both tedious and easily-forgotten to religiously include .ConfigureAwait(false) in libraries. While the default behavior does make sense, the default should be able to be defined in the csproj file. Allowing a flag such as <DefaultAwaitConfiguration>false</DefaultAwaitConfiguration> would be of great help

Describe the solution you'd like

Allow a sinple declaration in the csproj xml (and similar for other .net languages) that changes the way the compiler builds the assembly. If this sets the default to false, then the developer could use .ConfigureAwait(true) in specific cases where that behavior is desired.

When the project file lacks the flag, the current default (true) should be used.

Additional context

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[KalleOlaviNiemitalo]

Similar things have been requested in

• [Proposal] Forcing ConfigureAwait(false) on assembly level csharplang#2542: an assembly-level attribute. The SDK could then generate this attribute, but I don't think that would be much more convenient than requiring the developer to add it to an AssemblyInfo.cs file.
• Proposal: Extension await operator to address scoped ConfigureAwait csharplang#2649: operator await as an extension method. Might be more difficult to integrate with an MSBuild property.
• Champion "Replace/original and code generation extensions" csharplang#107 (comment) and Proposal: An algorithm for composable rewriting of expressions csharplang#3633: source generator replacing await expressions with ones that also call ConfigureAwait.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[CyrusNajmabadi]

Closing out as a dupe. Please use the existing csharplang discussions for this.