Use "href" template literals for safe-by-construction URL strings

[tsibley]

Avoids having to write out encodeURIComponent(), which is quite a mouthful!

Testing

• [x] Checks pass

[tsibley]

In discussion in Slack, @joverlee521 suggested uri instead of href. I'd be fine with this name too.

[tsibley]

uri's probably better, even if href feels cuter to me, so I renamed it here.

[tsibley]

@joverlee521 Fair enough! I added comments and repushed.