cvm-rs: merge guac and jpeg libs together into one

doesn't really need to be two seperate libraries. also preperation for other funnies

the build script has been replaced with a much saner justfile which uses much saner "yarn workspace" invocations instead of blindly cding all over the place

cvm-rs/index.js

@@ -0,0 +1,6 @@
+// *sigh*
+import { createRequire } from 'module';
+const require = createRequire(import.meta.url);
+
+export let {guacDecode, guacEncode, jpegEncode} = require('./index.node');
+