feat: esm

[florian-lefebvre]

Closes #2981

I kept this PR as minimal as I could. It introduces esbuild to be able to compile ESM to CJS to support both:

• I had to migrate lib to ESM because esbuild doesn't support transforming require() into import
• I had to write a little esbuild plugin to transform TLAs into require()

Things left to do where I'll need some help:

• I added a build script for esm/cjs but I'm not sure how it relates to install/build.js
• I'm not sure how tests are currently setup so unsure how to properly test esm/cjs
• I left some require() calls in libvips.js because they only seem consumed by binding.gyp

[florian-lefebvre]

Conditional exports are not supported by ESM but it doesn't matter here because importing the module will throw as needed

[lovell]

This is great, thank you for doing the hard work Florian, and at less of an impact in terms of changed code than I had imagined, merci donc d'avoir fait simple.

For the v0.35.x releases I'd like to maintain compatibility with versions of Node.js where ESM isn't fully available and then I suspect the v0.36.x releases (or maybe v1.0.x if I'm feeling lucky after 13 years) is the place for this to land and wish CommonJS bon voyage.

As an aside, I've been invited to (and accepted) the Astro event in London in a few weeks and spotted your name on the list so I might be able to thank you in person for this.

[florian-lefebvre]

Glad I can help :) Yeah I saw you on the list for the event, looking forward to meeting you! I'll give a talk on fonts

Btw I was thinking about this PR during the weekend and I don't know if the packages under npm can be updated to ESM yet. Maybe worth waiting for 0.36 or 1.0 because altho it's just matter of importing the .node file, not sure if that'd work for a CJS project