Better handling of the font face

[JarvyJ]

I don't like that it has to be next to the binary to work. Some options to explore:

• see if the font can be embedded in the codebase
• look for the font in a couple of locations
• check if it exists where system fonts are

It might be nice to let folks specify a custom font? I do want to keep flags limited, but if folks want it, then maybe. Maybe just load "font.ttf" in the directory you're in if it's available.

I'm not exactly sure what how other applications handle fonts from a commandline perspective.

Once this has been sorted, update the docs with the --display flag.

[JarvyJ]

Decided to go with just embedding it for now. I had to mod in ExportFontAsCode to raylib-go and then write a bit of code to load it. But it seems to work great!