feat(build): adds ESM outputs, separate types into lib/types dir

[bkrem]

• Towards fixing tree/index.js require() breaks with node 18, nextjs13, react18 - error recommends using import instead #418
• Follow-up to reverted feat(build): adds ESM outputs, separate types into lib/types dir #422.
  • Above seemed to work fine at first during my testing but then later surfaced another error ERR_UNSUPPORTED_DIR_IMPORT, due to ESM modules not resolving directory imports the way node does.