Distribute types as is (#8720)

I had initially seen some oddities around type augmentation for type definitions in subdirectories of `types`, and using Rollup seemed to help with that. However, now that all of Chart.js's main types are directly under `types`, there seems to be no need for this.

This simplifies the build process, since it no longer needs to use rollup-plugin-dts.

It also improves some third-party tools. For example, I'm in the habit of using WebStorm's "Go To Declaration or Usages" hotkey with third-party TypeScript definitions as a quick way of getting more information about an API. With the Rollup-generate types, that works poorly; WebStorm goes to the imported-and-re-exported symbol within the barely-readable machine-generated dist/chart.esm.d.ts file, and I have to navigate two more hops to find the actual definitions.

MAINTAINING.md

@@ -13,7 +13,7 @@ Chart.js relies on [Travis CI](https://travis-ci.org/) to automate the library [
 Creation of this tag triggers a new build:
 
 * `Chart.js.zip` package is generated, containing dist files and examples
-* `dist/*.js` and `Chart.js.zip` are attached to the GitHub release (downloads)
+* `dist/*.js`, `types/*.ts`, and `Chart.js.zip` are attached to the GitHub release (downloads)
 * A new npm package is published on [npmjs](https://www.npmjs.com/package/chart.js)
 
 Finally, [cdnjs](https://cdnjs.com/libraries/Chart.js) is automatically updated from the npm release.

package.json

@@ -8,7 +8,7 @@
   "unpkg": "dist/chart.min.js",
   "main": "dist/chart.js",
   "module": "dist/chart.esm.js",
-  "types": "dist/chart.esm.d.ts",
+  "types": "types/chart.esm.d.ts",
   "keywords": [
     "canvas",
     "charts",
@@ -28,9 +28,9 @@
     "auto/**/*.js",
     "auto/**/*.d.ts",
     "dist/*.js",
-    "dist/*.d.ts",
     "dist/chunks/*.js",
-    "dist/chunks/*.d.ts",
+    "types/*.d.ts",
+    "types/helpers/*.d.ts",
     "helpers/**/*.js",
     "helpers/**/*.d.ts"
   ],
@@ -84,7 +84,6 @@
     "rollup": "^2.41.4",
     "rollup-plugin-analyzer": "^4.0.0",
     "rollup-plugin-cleanup": "^3.2.1",
-    "rollup-plugin-dts": "^3.0.1",
     "rollup-plugin-istanbul": "^3.0.0",
     "rollup-plugin-terser": "^7.0.2",
     "typedoc": "^0.20.32",

rollup.config.js

@@ -1,6 +1,5 @@
 const analyze = require('rollup-plugin-analyzer');
 const cleanup = require('rollup-plugin-cleanup');
-const dts = require('rollup-plugin-dts').default;
 const json = require('@rollup/plugin-json');
 const resolve = require('@rollup/plugin-node-resolve').default;
 const terser = require('rollup-plugin-terser').terser;
@@ -11,10 +10,6 @@ const inputESM = {
   'dist/chart.esm': 'src/index.esm.js',
   'dist/helpers.esm': 'src/helpers/index.js'
 };
-const inputESMTypings = {
-  'dist/chart.esm': 'types/index.esm.d.ts',
-  'dist/helpers.esm': 'types/helpers/index.d.ts'
-};
 
 const banner = `/*!
  * Chart.js v${pkg.version}
@@ -84,20 +79,4 @@ module.exports = [
       indent: false,
     },
   },
-  // ES6 Typings builds
-  // dist/chart.esm.d.ts
-  // helpers/*.d.ts
-  {
-    input: inputESMTypings,
-    plugins: [
-      dts()
-    ],
-    output: {
-      dir: './',
-      chunkFileNames: 'dist/chunks/[name].ts',
-      banner,
-      format: 'esm',
-      indent: false,
-    },
-  }
 ];

types/index.esm.d.ts

@@ -1,17 +1,3 @@
-/**
- * Top-level type definitions. These are processed by Rollup and rollup-plugin-dts
- * to make a combined .d.ts file under dist; that way, all of the type definitions
- * appear directly within the "chart.js" module; that matches the layout of the
- * distributed chart.esm.js bundle and means that users of Chart.js can easily use
- * module augmentation to extend Chart.js's types and plugins within their own
- * code, like so:
- *
- * @example
- * declare module "chart.js" {
- *   // Add types here
- * }
- */
-
 import { DeepPartial, DistributiveArray, UnionToIntersection } from './utils';
 
 import { TimeUnit } from './adapters';