Check if final debounce URL's hostname has at least eTLD + 1

[ShivanKaul]

For AMP URLs (and there will probably be others), there are cases where the embedded target URL in the original URL that we want to debounce does not have a scheme, for e.g. https://theguadian.ampproject.org/c/s/www.newsarticleonguardian.com -- www.newsarticleonguardian.com is not a valid URL (and hence not parsed as one at least in Chromium and also by iOS it looks like) because it does not have a scheme. We create the right debounce URL by using a new property called prepend_scheme : http | https as described in #23121

The trouble is that if the original URL looks something like https://theguadian.ampproject.org/c/s/foo, and prepend_scheme is https, then we debounce to https://foo/, which is not actually a valid website, even though https://foo/ is technically a valid URL.

The proposed solution is (@fmarier):

1. Once you have a valid URL, extract the hostname.
2. Check that the hostname has at least an eTLD + 1 (e.g. example.com -> [example, com] ✅; http://foo/ -> [foo] ❌).
3. Reject the URL if the hostname doesn't have at least an eTLD + 1.

We should do this for all debounce actions.

[ShivanKaul]

@pilgrim-brave @pes10k

[pilgrim-brave]

Sure

[pes10k]

lgtm