Refactor: Make WebViewHTML an official export

This is based on [this comment](https://github.com/MetaMask/metamask-mobile/pull/10214#discussion_r1684283081) done by Zbigniew which states:

_(should) make it an official export that doesn't depend on the dist/browserify part of the path so that changing the path is not a breaking change.

Also, since it's being built anyway, there's nothing stopping you from generating a JS or JSON file with the html string embedded in it that's easy to import and type without relying on specific bundler features._