Add Exchanges with `HBAR-BTC` and `BTC-USD` pairs as well

**Summary**
Currently we only use exchanges that provide `HBAR-USD` pair. 
We can support more exchanges by implementing a feature that calculates HBAR-USD pair from an exchange that **has** 
`HBAR-BTC` and `BTC-USD` pairs but **no** `HBAR-USD` pair. 