"Run all tests in folder" / "Debug all tests in folder"

To match it, we should probably also rename "Start Debugging"/"Run without debugging" to include "tests" when on a test file.

@connor4312 before I do this, do you think it would make sense to have this in VS Code directly (that is, an option to "run tests in file" and "run tests in folder" in the explorer context menu, which just does the same as filtering to that file/folder in the Test Runner and running them)? I've had a few users ask how best to run tests from the Explorer (in Android Studio/IntelliJ, they can be run from the explorer tree like that).