646: Add error message for webapp startup hang

[telackey]

This fixes three issues:

1. webapp-build command should output something about the container built #644 (build output)
2. webapp container hangs on startup with no error message #646 (error on startup)
3. automatic env quote handling (related to 2)

For the build output we now have:

#################################################################

Built host container for /home/telackey/tmp/iglootools-home with tag:

    cerc/iglootools-home:local

To test locally run:

    docker run -p 3000:3000 cerc/iglootools-home:local

For the startup error, it was hung waiting for the "success" message from the next generate output (itself a workaround for a nextjs bug fixed by this PR we submitted: vercel/next.js#58276).

I added a timeout which will cause it to wait up to a maximum n seconds before issuing:

ERROR: 'npm run cerc_generate' exceeded CERC_MAX_GENERATE_TIME.

On the quoting itself, I plan on adding a new run-webapp command, but I realized I had a decent spot to do effect the quote replacement on-the-fly after all when I am already escaping the values for insertion/replacement into JS.

The "dequoting" can be disabled with CERC_RETAIN_ENV_QUOTES=true.