feat: Enable tests to also run for TestableIO MockFileSystem#356

vbreuss wants to merge 6 commits into

mainTestably/Testably.Abstractions:mainfrom

topic/add-tests-for-system.io.abstractions.testinghelperTestably/Testably.Abstractions:topic/add-tests-for-system.io.abstractions.testinghelperCopy head branch name to clipboard