[search addon] Make compatible with Trusted Types

[vrana]

https://web.dev/trusted-types/ doesn't allow string innerHTML assignments. This change avoids it by using DOM instead.

[marijnh]

This looks good, in general, but would you be open to adding a feature to el where you can pass children as extra arguments, so that the code gets a bit less verbose? Something like

for (let i = 2; i < arguments.length; i++) {
  let child = arguments[i]
  element.appendChild(typeof child == "string" ? document.createTextNode(child) : child)
}

[vrana]

Done.

[marijnh]

Merged as 68d3399, updated in 3362178 (there was an undefined reference to dialogText in the replace code)

[vrana]

Thanks.