Warn user when settling a globally settled asset

**Is your feature request related to a problem? Please describe.**
https://bitsharestalk.org/index.php?topic=27268.msg323170#msg323170
> Greetings, I have an error settling 0.11377283 BitBTC.
at 2018-10-15 23:46:36 in the block / 31395459/44
missing translation: en.operation.asset_settle_instant
>
>Very strange. The operation was resolved instantly, instead of 24 hours, and for a price much lower than that marked by the witness. What has happened?

>Thanks, I did not know that there had been a black swan event in BitBTC. Nor that the feed price was not the real one.
> The DEX should clearly warn of this type of circumstances, showing the actual status of a Smart Asset. It is not acceptable that the feed price shown causes confusion.

**Describe the solution you'd like**
For assets that are globally settled already, we should warn the user when she tries to settle, e.g. show the global settlement price. If there is already a warning about the 24 hours delay (IMHO we should have), we should check whether the asset has been globally settled to determine which warning to show.

By the way, perhaps it's better to show the globally-settled status and perhaps the price on market page. About asset page, there is already an issue https://github.com/bitshares/bitshares-ui/issues/1119.

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
We've added a warning when settling is worse than buying from market: https://github.com/bitshares/bitshares-ui/issues/1794 , situation caused by this issue is similar.

Review the existing warning added for issue 1794 and the related asset-page issue 1119 before locating the settlement flow in the BitShares UI. Confirm how the UI detects a globally settled asset and obtains its settlement price. Done means a user attempting to settle receives a clear global-settlement warning with the relevant price, rather than the normal delay warning.

Written by the indexing model from the issue text.