Remove Node dependencies from @datocms/cma-client

Right now cma-client (not cma-client-node) isn’t usable in a Cloudflare Workers context where node-compat isn’t available (Cloudflare Pages projects).

There aren’t too many Node-specific things here – even though this list of failed 'require’s below is pretty long – so I think sorting this shouldn’t be too tough? Maybe?

There’s been some work addressing this sort of thing in relation to Vercel’s Edge Functions; taking care of Workers as well would be really helpful. Hopefully it’s not too big a lift to attempt.