Add BTS to withdraw page

**Is your feature request related to a problem? Please describe.**

We have BTS in the deposit page but not in the withdraw page. People are confused when trying to "withdraw" BTS.

**Describe the solution you'd like**

Add BTS into the list, if the user has BTS in balance.

Show a descriptive message E.G. "if you want to withdraw BTS to an exchange, please follow the deposit instructions on the exchange, find the deposit address (account name) and the MEMO required to credit your funds on the exchange, fill them into the form below".

Show a normal withdrawal with "TO", "MEMO", fees, "withdraw" button, "cancel" button.

**Describe alternatives you've considered**

Alternatively we can provide a link to the send page.

**Additional context**

Start by locating the existing BTS entry on the deposit page and the asset list or entry point for the withdraw page; compare the send-page alternative. Confirm the BTS exchange guidance and the expected TO, MEMO, fee, withdraw, and cancel states. Done means BTS is available to users with a BTS balance and the requested instructions and withdrawal controls are present.

Written by the indexing model from the issue text.