This adds a completely separate frontend based on React because I
found that code gen works better with React once the application gets
bigger. In particular it was getting very hard to move past add
connectors and actions.
The idea is to replace the standard UI with this once it has been
tested. But for now it is available at /app in addition to the
original at /
Signed-off-by: Richard Palethorpe <io@richiejp.com>
