VS Code Dev Integration Support

[chlafreniere]

To avoid bouncing between VS Code + VS for dev purposes, let's ensure that we make it easy for devs to leverage VS Code in this repo:

• .vscode folder with easy debugging/test execution
• "Test explorer" integration
• Linting - is .editorconfig the suggested approach?
• Codespaces 😄

[Charles-Gagnon]

Look at other C# projects for how best to set this stuff up