Always use denom with currency amounts

I have noticed that Bond/Unbond msgs in the [virtual staking doc](https://github.com/osmosis-labs/mesh-security/blob/main/docs/consumer/VirtualStaking.md#interface) do not contain a denom value for example. There should only be one staking token but it would be better have this explicitly set by the contract via `Coin` type. This makes it more readable for humans and future proof.