Make return key equivalent to go button when location field is focused

[atbrakhi]

Adds Return key that is equivalent to go button when location field is focused in Minibrowser mode.

• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes part of [meta] Minibrowser #30049

[delan]

This is a good start, though there are a couple parts of the behaviour I think we can improve:

• the location sometimes reverts to the old value while loading, which may be confusing
• we should also accept numpad enter, not just the normal return key

[atbrakhi]

the location sometimes reverts to the old value while loading, which may be confusing

I will look into this part separately, as it is not the result of changes in this PR. I have added it as a TODO in #30049

we should also accept numpad enter, not just the normal return key

unfortunately egui does not have support for numpad enter. Docs here :(
I will add it as TODO in meta issue, so that we can check back later.

[delan]

Thanks, and good catch, I didn’t realise the location bug was pre-existing.

[servo-wpt-sync]

🛠 These changes could not be applied onto the latest upstream WPT. Servo's copy of the Web Platform Tests may be out of sync.