This lets us use all our normal JS tooling like prettier, esline and babel on the splash screen JS. At runtime the JS file is read and inlined into the HTML. This commit also switches us to use a CSP hash rather than a nonce for the splash screen.
Prior to v89, Firefox has bugs with document.execCommand("insertText"): https://bugzil.la/1220696
This commit introduces some variables to browser-detect, and therefore wraps the entire logic in an IIFE to avoid state leaking. (`let`/`const` are not supported on older browsers)
Previously we would only expand the main `<noscript>` element for older browsers. This commit ensures that we expand all noscript elements on the page, including the one used by the splashscreen to hide itself on the no-js view.
All files under `app/assets/javascripts/scripts` will be run through babel, given sourcemaps, and output under `/assets/{name}.js`. This is another step towards removing our sprockets dependence.
