Include both StepLang.dll build timestamp as well as step.exe (StepLang.CLI) build timestamps in info

[ricardoboss]

The current output of step --info looks like this:

 Build Date  2023-12-05 01:38:59 UTC                             
    Version  8ba11c7b651d6c2d2b7095ff71bc1c014bf5de90 (2.0.1+273)
     Branch  main
CLR Version  8.0.0
 OS Version  Microsoft Windows 10.0.22631 (X64)

This was generated using a framework-dependent build of STEP, where the StepLang.dll was exchanged with a newer version. The build date should reflect that, either by providing build timestamps from both DLLs or only the one from StepLang.dll.