TypeScript Core

[chharvey]

The first of several PRs in an attempt to break up #8826 into smaller parts. This PR sets up core typescript functionality and ports over only the top-level types, constants, and enums of the JS API.

Changes:

• adds root-level ts/ folder with README.md, package.json, tsconfig.json, and other project files
• updates root-level CMakeLists.txt, exporting needed variables & methods (like HEAP8) from Emscripten into the JS build
• ts/src/-pre.ts imports the Emscripten-built Binaryen function, calls and awaits it, and exports that as an internal object called BinaryenObj (AssemblyScript calls this object binaryen and exports that publicly).
• ts/src/**: the typescript library sits on top of the Emscripten artifact. it accesses the WASM bindings on BinaryenObj imported from -pre.ts.
• entrypoint ts/src/binaryen.ts for users, exporting all the parts of the public-facing API. Users use a namespace import instead of a default import:

  import * as binaryen from "binaryen.ts";
  

  (this better aligns with the ES Modules standard since it’s no longer a proper object).
  users will still use the same API (binaryen.ExpressionRef, binaryen.i32, binaryen.Module, etc.)
• starting some Node.JS tests at ts/tests/. hopefully this will take some of the weight off the python tests

Non-Changes:

• original binaryen.js-post.js file has not been touched; the tentative plan is to complete the TS migration before phasing out the JS code (unless decided otherwise by repo maintainers)
• python tests also haven’t been touched for now, but maybe a future PR will work on migrating them to Node.JS

API Deprecations (see ts/src/-deprecations.ts for full list; will evolve with more PRs):

• enum names have been singularized (e.g. binaryen.Features → binaryen.Feature)
• deprecations are still accessible as their old symbols (users can still use binaryen.Features, but there is a doc-comment @deprecated warning for intellisense support)

Get started:

brew install node # includes npm
cd ts/
npm ci          # downloads dependencies
npm run make    # rebuilds out-of-tree into ../build/ and copies the built js to ./build/
npm run check   # runs the python tests
npm run compile # compiles typescript to ./dist/
npm run test    # runs the node tests

See ts/package.json, ts/README.md, and ts/docs/API-Overview.md (in this PR) for details.