Refactored module exports; (#5162)

* Refactored build pipeline;
Added module exports tests;
Added missing ESM export for parity with Axios factory;
Added `toFormData`, `formToJSON`, `isAxiosError`, `spread`, `isCancel`, `all` as named export to `index.d.ts`;

* Added ESM entry test;

* Updated README.md `installing` section;

* Added TypeScript importing test;
Added missed `CanceledError` & `AxiosHeaders` to `AxiosStatic` interface;

* Exclude `/test/module/` from tslint;

test/typescript/axios.ts

@@ -6,7 +6,13 @@ import axios, {
   AxiosAdapter,
   Cancel,
   CancelTokenSource,
-  Canceler, AxiosProgressEvent, ParamsSerializerOptions
+  Canceler, AxiosProgressEvent, ParamsSerializerOptions,
+  toFormData,
+  formToJSON,
+  all,
+  isCancel,
+  isAxiosError,
+  spread
 } from 'axios';
 
 const config: AxiosRequestConfig = {
@@ -354,11 +360,28 @@ const promises = [
 
 const promise: Promise<number[]> = axios.all(promises);
 
+// axios.all named export
+
+(() => {
+  const promises = [
+    Promise.resolve(1),
+    Promise.resolve(2)
+  ];
+
+  const promise: Promise<number[]> = all(promises);
+})();
+
 // axios.spread
 
 const fn1 = (a: number, b: number, c: number) => `${a}-${b}-${c}`;
 const fn2: (arr: number[]) => string = axios.spread(fn1);
 
+// axios.spread named export
+(() => {
+  const fn1 = (a: number, b: number, c: number) => `${a}-${b}-${c}`;
+  const fn2: (arr: number[]) => string = spread(fn1);
+})();
+
 // Promises
 
 axios.get('/user')
@@ -396,6 +419,12 @@ axios.get('/user', {
     const cancel: Cancel = thrown;
     console.log(cancel.message);
   }
+
+  // named export
+  if (isCancel(thrown)) {
+    const cancel: Cancel = thrown;
+    console.log(cancel.message);
+  }
 });
 
 source.cancel('Operation has been canceled.');
@@ -407,12 +436,28 @@ axios.get('/user')
     if (axios.isAxiosError(error)) {
       const axiosError: AxiosError = error;
     }
+
+    // named export
+
+    if (isAxiosError(error)) {
+      const axiosError: AxiosError = error;
+    }
   });
 
 // FormData
 
 axios.toFormData({x: 1}, new FormData());
 
+// named export
+toFormData({x: 1}, new FormData());
+
+// formToJSON
+
+axios.toFormData(new FormData());
+
+// named export
+formToJSON(new FormData());
+
 // AbortSignal
 
 axios.get('/user', {signal: new AbortController().signal});