POC - Start converting to monorepo

Completed work:

* Copy a few modules to `packages/`
* Upgrade Yarn to v3
* Add Yarn workspaces
* Add Yarn constraints for `package.json` in root and package
* Reconfigure TypeScript support new structure
* Reconfigure Jest to support new structure

Remaining work:

* TypeDoc — it doesn't seem to support TypeScript project references, so
  we may have to generate docs for each package individually or figure
  out something else
* ESLint — the `node` and `import` plugins are tripping up on imports
  which are aliases — we either need to disable the appropriate rules or
  get the plugins to recognize `tsconfig.json` appropriately

.eslintrc.js

@@ -69,6 +69,17 @@ module.exports = {
       'error',
       { matchDescription: '^[A-Z`\\d_][\\s\\S]*[.?!`>)}]$' },
     ],
+
+    // These options do not support our monorepo structure, which houses
+    // two levels of `package.json`'s instead of just one.
+    'import/no-extraneous-import': 'off',
+    'import/no-extraneous-dependencies': 'off',
+    'node/no-extraneous-import': 'off',
+    'node/no-extraneous-dependencies': 'off',
+
+    // TODO: This isn't working for `jest.config.ts` (see first line). Look into
+    // why.
+    'node/no-unpublished-import': 'off',
   },
   settings: {
     'import/resolver': {

.gitignore

@@ -1,18 +1,82 @@
-# node
-npm-debug.log
-yarn-error.log
-npm-debug.log
-yarn-error.log
-node_modules
-package-lock.json
-
-# tarball from `yarn pack`
-*.tgz
+.DS_Store
+dist/
+coverage/
 
-# eslint cache
-.eslintcache
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
 
-.DS_STORE
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Coverage directory used by tools like istanbul
 coverage
-dist
-docs
+*.lcov
+
+# nyc test coverage
+.nyc_output
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+
+# TypeScript cache
+*.tsbuildinfo
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Microbundle cache
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+.env.test
+
+# Stores VSCode versions used for testing VSCode extensions
+.vscode-test
+
+# ---- Additions/changes beyond the module template ----
+
+# yarn v3 (w/o zero-install)
+# See: <https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored>
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions
+
+# Docs
+docs/

.yarnrc.yml

@@ -0,0 +1,16 @@
+# We use allow-scripts to manually enable scripts and then run them
+enableScripts: false
+
+# This is necessary right now for TypeScript to find @types/* packages
+nodeLinker: node-modules
+
+plugins:
+  # Provides `yarn workspaces foreach`, etc.
+  - path: .yarn/plugins/@yarnpkg/plugin-workspace-tools.cjs
+    spec: "@yarnpkg/plugin-workspace-tools"
+  # Provides `yarn constraints`
+  - path: .yarn/plugins/@yarnpkg/plugin-constraints.cjs
+    spec: "@yarnpkg/plugin-constraints"
+
+# The current version of Yarn we're using
+yarnPath: .yarn/releases/yarn-3.2.1.cjs