Implement basic Nabla communication logic using hard-coded contract addresses

[ebma]

This is an overarching ticket for the Nabla smart contract implementation. We will already try to implement the logic without having an indexer but using hard-coded smart contract addresses.
I create this ticket because I only want to have one PR instead of having separate PRs for each ticket.

The related tickets are

• Add liquidity to Nabla backstop pool #119
• Remove liquidity from the Nabla backstop pool  #141
• Remove liquidity from Nabla swap pool #142
• Add liquidity to Nabla swap pool #116
• Fetch user liquidity info for Nabla backstop pool #118
• Fetch swap pools info for Nabla #114

[ebma]

I'm closing this because it is not needed anymore.