CI Pre-build and download

[konsumer]

We could speed up install with CI builds for lots of targets, and download on install, or just include many with the npm module.

I think some good targets would be:

• osx intel 64bit
• osx M1
• windows intel 64bit
• linux intel 64bit

and then, maybe as secondary targets:

• windows intel 32bit (I dunno if anyone uses this...)
• linux arm 32bit (pi)
• linux arm 64bit (pi4)

On any targets not covered, it should work the same as it does now, so it's really just a way to speed it up (and not require cmake/c tools/build-time) on most the common platforms.

[konsumer]

Looks like we already have some CI in place. I am going to do some local testing with act to see if I can improve it, and get it building for more targets, then work on the entry-point to prefer a pre-built from CI over cmake-built.

[konsumer]

I started work on this with a fancier build-matrix. I also merged test & build to optimize cacheing, and set it to run on every push/PR, so we have a nice test indicator & build to play with on every platform.

remaining issues

• I had to skip a few tests. Not sure if they worked before raylib4, but they should get a closer look.
• I can easily matrix node-version & OS, but not arch. Arch can sort of be handled with this but only for linux, so that leaves out mac M1 & non-64bit windows. M1 users should be good with rosetta, but maybe they should just use native cmake fallback, too. I think it's fine, as long as the build script works, but it might make sense to add a separate pi build (maybe just on tagged release?) since it is very slow to build there.
• still need to work out how to use these build artifacts in the library. I setup CI so it skips things like npm's postinstall, so we can use that hook to check & download things (and build if needed.) Normally I would use tag to setup a release and npm publish and point to latest release, but maybe we want to set this up differently?
• do we need to test all these node versions? supporting just 16.x would simplify & speedup (3X) and should basically apply to the older versions. They seem to produce interchangeable .node files.

[RobLoach]

That's awesome! Nicely done.

[konsumer]

I added a stub setup in tools/postinstall.js. It will load very fast if you have build/Release/node-raylib.node and download a tagged release if we have one (from CI) or build it, if not. It only installs build-tools if you actually need to build, so people on a supported platform will be able to use it, even if they don't have cmake/etc.