Enhance 'install-powershell.ps1' to work on Linux and macOS too. A user can install release version or daily powershell core on Linux and macOS.
When `-AddToPath` is specified:
- On Windows, add the absolute destination path to the 'User' scope environment variable 'Path';
- On Linux, make the symlink '/usr/bin/pwsh' points to "$Destination/pwsh";
- On MacOS, make the symlink '/usr/local/bin/pwsh' points to "$Destination/pwsh".