fix: VS code will now properly import operators, et al (#6276)

- Adds typesVersions, enforcing TypeScript >= 4.2.
- Adds some superfluous references required for TS and VS Code to find proper import locations for our strange deep import sites.
- Independantly tested by building the package and installing it locally in another project, then testing in VS code.

Fixes #6067
Related microsoft/TypeScript#43034

package.json

@@ -5,7 +5,12 @@
   "main": "./dist/cjs/index.js",
   "module": "./dist/esm5/index.js",
   "es2015": "./dist/esm/index.js",
-  "types": "./dist/types/index.d.ts",
+  "types": "index.d.ts",
+  "typesVersions": {
+    ">=4.2": {
+      "*": ["dist/types/*"]
+    }
+  },
   "sideEffects": false,
   "exports": {
     ".": {

src/index.ts

@@ -1,3 +1,18 @@
+//////////////////////////////////////////////////////////
+// Here we need to reference our other deep imports
+// so VS code will figure out where they are
+// see conversation here:
+// https://github.com/microsoft/TypeScript/issues/43034
+//////////////////////////////////////////////////////////
+
+// tslint:disable: no-reference
+/// <reference path="./ajax/index.ts" />
+/// <reference path="./fetch/index.ts" />
+/// <reference path="./operators/index.ts" />
+/// <reference path="./testing/index.ts" />
+/// <reference path="./webSocket/index.ts" />
+// tslint:enable: no-reference
+
 /* Observable */
 export { Observable } from './internal/Observable';
 export { ConnectableObservable } from './internal/observable/ConnectableObservable';