Move @polkadot/x-{fetch,textdecoder,textencoder,ws} (#737)

* Move @polkadot/x-{fetch,textdecoder,textencoder,ws}

* Adjust copyrights

* Fix jest aliassing

* tsconfig resolution

packages/x-textdecoder/src/browser.ts

@@ -0,0 +1,17 @@
+// Copyright 2017-2020 @polkadot/x-textencoder authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+export default typeof TextDecoder === 'undefined'
+  ? class {
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars,no-useless-constructor
+    constructor (_: 'utf-8') {
+      // nothing
+    }
+
+    decode (value: Uint8Array): string {
+      return value.reduce((str, code): string => {
+        return str + String.fromCharCode(code);
+      }, '');
+    }
+  }
+  : TextDecoder;

packages/x-textdecoder/src/node.ts

@@ -0,0 +1,8 @@
+// Copyright 2017-2020 @polkadot/x-textencoder authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import { TextDecoder as NodeTextDecoder } from 'util';
+
+export default typeof TextDecoder === 'undefined'
+  ? NodeTextDecoder as unknown as typeof TextDecoder
+  : TextDecoder;

packages/x-textdecoder/src/typeCheck.ts

@@ -0,0 +1,8 @@
+// Copyright 2017-2020 @polkadot/x-textdecoder authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import BrowserTD from './browser';
+import NodeTD from './node';
+
+console.log(new BrowserTD('utf-8').decode(new Uint8Array([1, 2, 3])));
+console.log(new NodeTD('utf-8').decode(new Uint8Array([1, 2, 3])));