CLI: display severity classification of each issue

[matiascabello]

Currently each issue found by Scout is displayed as follows:

warning: Division before multiplication might result in a loss of precision
    --> pallets/dapp-staking/src/lib.rs:1722:41
     |
1722 |                         reward_per_rank.saturating_mul(ranks_sum.into());
     |                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = help: Consider reversing the order of operations to reduce the loss of precision.
     = note: `#[warn(divide_before_multiply)]` on by default

Expected output

Display the severity classification of each issue.