Compress the wasm artifact that we bundle into the viewer

[jleibs]

While working on:

• When loading on web, match style and show a progress indicator while wasm is loading #2421

I noticed that google is gzipping the wasm artifacts during loading which brings us from 13.5 MiB -> 4.4 MiB. The content is then served with Content-Encoding: gzip.

It seems worth taking the same approach to shave down binary/library/transfer size with working with the embedded web-viewer.

Related: #2422