Smartcoin borrow modal doesn't use median_price during individual settlement

**Describe the bug**

New BSRM's were introduced to the Bitshares core a while ago, one of them is the 'individual settlement funds' option, which if a position has been settled then it freezes the settlement price until it's cleared, however it should be using the median price so that new positions can be borrowed into existence.

**To Reproduce**

Go to the HONEST.BTC_BTS market, click the 'borrow' button.

See that the current settlement feed price is equal to the individual settlement fund rate.

Unable to borrow new smartcoins via modal using the median price.

Try to borrow new

**Expected behavior**

Able to create a new smartcoin position using the median price feed, whilst there's an individual settlement fund.

Reproduce the issue in the HONEST.BTC_BTS market by opening the borrow modal during an individual settlement. Trace how the modal selects the settlement feed price versus the median price; done means a new smartcoin position can be created using the median price while individual settlement funds exist.

Written by the indexing model from the issue text.