Integrate resinator errors with Zig using std.zig.Server and ErrorBundle

This takes the code that was previously in src/Compilation.zig to turn resinator diagnostics into Zig error bundles and puts it in resinator/main.zig, and then makes resinator emit the resulting error bundles via std.zig.Server (which is used by the build runner, etc). Also adds support for turning Aro diagnostics into ErrorBundles.