Define a load_fluidsynth() function

[cclauss]

Let's document which library is used by each operating system.

def load_libfluidsynth(debug_print: bool = False) -> str:
    """
    macOS X64:
    * 'fluidsynth' was loaded as /usr/local/opt/fluid-synth/lib/libfluidsynth.dylib.
    macOS ARM64:
    * 'fluidsynth' was loaded as /opt/homebrew/opt/fluid-synth/lib/libfluidsynth.dylib.
    Ubuntu X86:
    * 'fluidsynth' was loaded as libfluidsynth.so.3.
    Windows X86:
    * 'libfluidsynth-3' was loaded as C:\tools\fluidsynth\bin\libfluidsynth-3.dll.
    """