Add consensus inflation rewards

[corverroos]

Problem to Solve

Our consensus chain doesn't collect any fees since it doesn't have a gas token. We currently burn execution rewards and xchain protocol doesn't accrue rewards in consensus chain either. We do however want to incentivise staking on the consensus chain.

A common way this is achieved in cosmos is via inflation, ie mint module. See details here.

Proposed Solution

• Design the mint inflation parameters.
• Enable the mint module

Note this will require a network-upgrade