feat(invariant): add basic metrics report

[grandizzy]

Motivation

Closes #3607 with basic approach #3607 (comment) (more complex impl to be looked up post 1.0 release)

• display a table with invariant fuzzed selectors and metrics under each invariant test (if run with show_metrics invariant config, inline or global, on true) as
  

Solution

• add InvariantMetrics struct and update during invariant runs: holds total number of calls, discarded runs (through vm.assume) and reverts per selector
• add helper fn to create and print metrics table

[mattsse]

cool

[yash-atreya]

lgtm!