Migrate SDK package to TypeScript "Project References"

[kraenhansen]

In an effort to lower complexity of our build / bundle process for the realm SDK package we'd like to explore migrating from using a bundler (we're currently using Rollup) into a pure TypeScript project (leveraging TypeScript Project References).

The immediate benefits that we expect this will bring:

• Simpler tooling:
  • One less tool to learn when approaching the project as a new developer.
  • Less components to depend on (which all have their limitations and bugs that we sometimes need to work around).
• Because of a bug in rollup-plugin-dts we need to use type aliases when reexporting types through the Realm namespace.
• Because we're bundling .d.ts with rollup-plugin-dts we need to co-locate the declaration of the Realm namespace with the Realm class and cannot move this to a separate file and leverage TypeScript "Module Augmentation".
• Transpiling to individual files instead of a bundle would:
  • Enable end-users bundlers to more easily shake unused code and
  • We'll have source-maps and declaration maps (enabling "go to definition" to jump straight to source code) enabled by default.
  • Enable us to export internal entry-points to
    • simplify our testing by moving unit tests into our "integration tests" and run these tests of internal primitives of the SDK on all supported platforms.
    • allow end-users to inject their own platform specific helpers (such as using the window.fetch in an Electron renderer process, etc.)
    • build / publish experimental packages hooking into our internal APIs.

I attempted to do this migration as part of #5853, but hit a couple of issues that I needed to find workarounds for:

• The Typescript compiler would emit .mjs files even when module was set to commonjs which would break the package upon import. I filed an issue for this, created a PR and found a temporary workaround.
• Although the Jest issue is closed, I found problems from Jest lacking support of export conditions out of the box and had to implement a custom resolver. I later transitioned into exporting via a separate package in an attempt to work around this.
• I was planning to rely on bundleDependencies to pull @realm/network-transport (and a new @realm/binding package) into the SDK's .tar.gz before uploading it to NPM. But this is not supported when using NPM workspaces (yet) :meow_sad: [BUG] Workspaces - bundledDependencies missing in tarball after npm pack npm/cli#3466