Themes contain both CSS and Snippets. The brewRenderer only cares about the CSS, but other components need the Snippets. Better to have the parent "editPage", etc. load the theme bundles and pass them down to each child that needs it, rather than trying to pass from the child up.
This also fixes the `metadataEditor.jsx` not being able to change themes live; A new theme bundle is now loaded when a new theme is selected, instead of only the first time the BrewRenderer mounts.
Also renamed to "fetchThemeBundle"
`renderStyle` is still necessary; it allows us to update the style live in the component render step as the user types into the style tab. Otherwise the style is only rendered once and never updates.
React also discourages directly editing the DOM ourselves, because it makes changes to the DOM that react cannot track; we should aim to provide all DOM writes inside of the component render function instead of using `document.createElement`, etc.
Too that end, this commit reduces the `loadAllStylesAndSnippets` function to just fetch and parse the data; actual rendering is moved back to `renderStyle()`
This removes the existing endpoints and replaces them with /theme.
/theme/:id - return a theme bundle containing all styling from this USER theme and any parents.
/theme/:engine/:id - return a theme bundle containing all styling from this STATIC theme and any parents
The theme bundle returns a marshalled JSON object containing:
styles - an array of strings representing the collected styles in loading order
snippets - an array ( currently empty ) of collected snippets.
The various bits of theme rendering code for <style> an style <link> have been swapped out with an 'onDidMount' call that loads the thendpoint and appends a series of <style> blocks to the brewRender's head.
This loses some caching advantages, but probably won't matter in the long run.
Ended up being a fairly straightforward change. A few ternaries got smooshed or inverted. Passes builtin and local tests. Need to compare on the test instance.
