Enable symlinks on Windows

[jeroenpf]

What

In #510 we implemented support for symlinks. Unfortunately, this only works for MacOS. When running Studio on Windows, PHP WASM mounts symlink nodes with invalid target paths such as /var/www/html/C:\Users\example\target-foo - we can not mount these paths because they are not POSIX compliant.

The root cause can likely be found in Emscripten and particularly the NODEFS filesystem, which we use to mount site directories and symlink targets. Further investigation will be needed to determine the exact problem.

Creating symlinks can be done as follows:
Using Windows terminal:
mklink /D symlink origin_dir (for directories)
mklink symlink origin_file (for files)

Using Powershell:
New-Item -Path symlink -ItemType SymbolicLink -Value origin

Why

Some (Windows) developers might want to utilize symlinks to include plugins, themes, or other files located outside of their Studio project.

How

Figure out how we can fix the invalid symlink targets so that we can properly mount on it.