chore: build the JS printer's modules

js/mod.rs merges bun's lib.rs and js/mod.rs, and declares the
printer's modules. Import sorting, JSDoc formatting and the embedded
languages of templates stand in as no-ops until they are ported onto
tidy: the printer then prints what Prettier prints with
embeddedLanguageFormatting off. The js feature is off by default until
the printer builds.