Remove wasm url extension check

[ansbbrooks]

Currently, when a wasm url is passed to createNamespace(), loader.load() checks if the url ends with .gz to handle Gzip archives.

This is a problem since urls do not have to have a .gz extension to serve a Gzip file.

For example, running a server that serves the VTK.wasm client .gz bundle at the following endpoint would fail the url check:

http://localhost/get_vtk_bundle

It is better to allow the Gzip decompressor to fail on its own if the downloaded resource is not a Gzip archive, and let the user specify what is at the end of their endpoint (since only they can know for sure).

In this PR, the createNamespace() function has the following signature:

createNamespace(url: string, config: object, wasmBaseName: string, urlIsGzipBundle: boolean)

[ansbbrooks]

@jourdain @jspanchu What are everyone's thoughts on this one?

[jspanchu]

I'm fine with the changes.