Fsdk,Fsdk.Tests(ArgsParsing): refactoring #1593

Job	Run time
macOS--dotnet6-and-mono	12m 23s
linux-oldLTS-github--dotnet-and-xbuild	9m 12s
linux-oldLTS-github--dotnet-and-msbuild	7m 55s
macOS--mono	5m 53s
linux-newLTS-github--dotnet-and-msbuild	8m 29s
linux-oldLTS-vanilla--stockmono	5m 37s
linux-oldLTS-vanilla--newmono	7m 35s
linux-newLTS-github--dotnet-and-xbuild	9m 19s
linux-newLTS-vanilla--dotnet6	7m 39s
linux-newLTS-vanilla--newmono	6m 11s
linux-newLTS-vanilla--stockmono	5m 21s
windows--legacyFramework	18m 53s
windows--dotnet6	9m 33s
sanity-check	1m 15s
publish	1m 9s
	1h 56m 24s

Provide feedback