Fix script execution on Windows host including device tree overlay generation

These commits allow the build-bitstream.py script to successfully execute on a Windows host including generating device tree overlays.

The build scripts were modified to only pass relative paths to the Libero TCL script to avoid TCL script arguments getting confused with the column in Windows absolute paths.

The generation of the device tree overlay now checks the host development platform's operating system and uses WSL when running on Windows to execute the device tree compiler. This approach uses the Windows installation of the Libero FPGA tools, allowing to inspect the FPGA design using the Lbero GUI on Windows. The added prerequisite is to install Windows Subsystem for Linux (WSL) on the Windows host and install the Linux device tree compiler within WSL.