Fix icons metadata missing from layout (#52673)
### What
This was an issue introduced in #52416 when we check the images and icons property while merging with static file conventions. Where we should check if the properties are present but we only checked if they value is falsy. So when you're using `icons` with array value it breaks.
Now we properly check all the possible case of `metadata.icons` value, so then decide if we are using the static file convention or the icons property of defined metadata.
Also add few more tests cases to cover icons resolving.
