Remove a deprecated library and replace with a native test shim.

    node-webcrypto-ossl has been deprecated. This module was created in
    2015 because at the time the Node team did not feel the need to
    have two crypto interfaces and they already had one before
    WebCrypto was defined

Refs: https://www.npmjs.com/package/node-webcrypto-ossl

Signed-off-by: Mike Fiedler <miketheman@gmail.com>

jsdom 13.2.0 added direct support for MutationObserver, and recommends
removing all workarounds. We're on version 19.0.

Refs: jsdom/jsdom#639 (comment)

Signed-off-by: Mike Fiedler <miketheman@gmail.com>

With `fetch()` being available to all modern browsers, we no longer need
to provide this polyfill.

Remove related `imports-loader` and `exports-loader` as well.

Signed-off-by: Mike Fiedler <miketheman@gmail.com>