Show workdir in alienv if present

[singiamtel]

Otherwise we're suggesting to the user to run a command that will fail

Output example:

% aliBuild build date -w 2

==> aliBuild can take the following packages from the system and will not build them:
      zlib

==> The following packages cannot be taken from the system and will be built:
      CMake

==> Packages will be built in the following order:
     - alibuild-recipe-tools@v0.2.5
     - curl@curl-7_70_0
     - CMake@v3.31.6
     - date@v3.0.3
==> Updating repositories: done
==> Compiling defaults-release@v1 (use --debug for full output): done
==> Compiling alibuild-recipe-tools@0.2.5 (use --debug for full output): done
==> Compiling curl@7.70.0 (use --debug for full output): done
==> Compiling CMake@v3.31.6 (use --debug for full output): done
==> Compiling date@v3.0.3 (use --debug for full output): done

==> Build of date successfully completed on `starforsaken'.
    Your software installation is at:

      /Users/sergio/wsp/CERN/code/alibuild/2/osx_arm64

    You can use this package by loading the environment:

      alienv enter -w 2 date/latest-o2

% alienv enter -w 2 date/latest-o2
Loading date/latest-o2
  Loading requirement: BASE/1.0
Currently Loaded Modulefiles:
 1) BASE/1.0   2) date/latest-o2

Key:
auto-loaded
Use alienv list to list loaded modules. Use exit to exit this environment.
[date/latest-o2] ~/wsp/CERN/code/alibuild $>
exit
```bash