build(client): generate a UMD bundle

[lpinca]

First commit

build(client): generate a UMD bundle
    
A UMD bundle can be used as a regular CommonJS module by bundlers and
included in other bundles.

Second commit

build(client): drop the .mjs extension
    
The .mjs extension is misleading as the generated bundle is not an
ECMAScript module and prevents bundlers from working properly.

[lpinca]

Assume the following code is saved in an index.js file.

const { BrowserStorage, SocketProvider } = require('@webcrypto-local/client');

// Use `BrowserStorage` and `SocketProvider`.

Creating a bundle with index.js as entry point and running it in the browser should work as expected.

[rmhrisk]

@lpinca I will have @microshine look at this but I am curious what app usage your working on? It is always neat to hear what people are doing with Fortify.

[lpinca]

@rmhrisk The plan is to use Fortify to create CAdES-BES signatures in the browser (I'm close to have a working demo) which will eventually be part of a much larger application.

[microshine]

22.06.2020  19:35            63 109 index.es.js
22.06.2020  19:35            63 529 index.js
22.05.2020  14:02    <DIR>          types
22.06.2020  19:36           580 724 webcrypto-socket.js
22.06.2020  19:36           226 158 webcrypto-socket.min.js
22.06.2020  19:35           156 767 webcrypto-socket.min.mjs
22.06.2020  19:35           345 992 webcrypto-socket.mjs

Current version of client:
index.js - commonjs library in ES5. For NodeJS
index.es.js - library in ES2015
webcrypto-socket[.min].js - bundled file for browser in ES5. Uses global variable WebcryptoSocket for all exports
webcrypto-socket[.min].mjs - bundled file for browser in ES2015. Uses global variable WebcryptoSocket for all exports

[lpinca]

You still get the global variable with this if you load the library in a <script> element. This allows the lib to be required and bundled with bundlers without forcing the user to use a <script> element and without exposing WebcryptoSocket in the global object.

The .mjs extension is used for ECMAScript modules and confuses webpack because webcrypto-socket{,min}.mjs are not ECMAScript modules.

[lpinca]

There are still other dependencies that force the user to use a <script> element, like protobuf but that is a different issue.