feat: streamline depending on zap by linking facil.io to module

[leroycep]

This means that all downstream users can simply put:

exe.root_module.addImport("zap", zap.module("zap"))`

in their build.zig instead of

exe.root_module.addImport("zap", zap.module("zap"));
exe.linkLibrary(zap.artifact("facil.io"));

This change should be backwards compatible. I updated some local code to use this change, and it didn't require any modifications to that build.zig. That means the old method will still work, but users will no longer have to manually link facil.io.

[renerocksai]

Wow! Nice!