[Feature Request]: Code optimization - retrieve module relative path through dedicated function

### Description

Implement helper function to retrieve the module relative path given the full path, e.g., `Get-FormattedModuleRelativePath`

Replace lines like
```powershell
$moduleRelative = $moduleRoot.Replace('\', '/').split('modules/')[1]
```
used e.g., by Pester test, with a call to that function