[FTS] UI: copy-to-clipboard curl doesn't handle escaping single quotes correctly

This index definition from MB-22931 has stop words with contractions, like...

I'm wasn't who's

So, there's single quotes there. When converted to the copy-&-pasted curl cmd-line example, those single quote's aren't backslashed, so pasting that curl example into a shell prompt doesn't work correctly, where the first single quote inadvertently ends the JSON payload.

Here's the problematic index definition...
https://gist.github.com/mschoch/60068e94a712d348f8ac445fd71d3e90