feat: implement `HasExtension` and `TrimEndingDirectorySeparator` for simulated `Path`#574

vbreuss merged 3 commits intomainTestably/Testably.Abstractions:mainfrom

topic/add-hasextension-and-trimendingdirectoryseparatorTestably/Testably.Abstractions:topic/add-hasextension-and-trimendingdirectoryseparatorCopy head branch name to clipboard