Implement an oracle interface for a 2-price oracle as required by Djed Shu

[ceilican]

See #20 for context.

The current oracle interface (https://github.com/DjedAlliance/Djed-Solidity/blob/main/src/IOracle.sol) assumes that the oracle provides only one price.

But Djed Shu needs an oracle that provides two prices.

Therefore, we need to do the following:

• duplicate IOracle.sol and rename it to IOracleShu.sol
• in IOracleShu.sol, replace the single readData function by a readMaxPrice and a readMinPrice functions.

[keshav-nischal]

I would like to work on this issue

[ceilican]

Thanks, @keshav-nischal !