Slight refactor

[feliam]

• Metric is a separated entity that gets updated similar to how metrics are updated

• checks are calculated based on pre/post states:
  pub async fn run(&self, pre_state: &State, post_state: &State) -
• metrics are updated the same way:
  pub fn update(&self, pre_state: &State, post_state: &State)

• A single current_state is maintained in the mainloop
  let current_state = Arc::new(RwLock::new(state));
• Initial height from config or tip
• States attempt to be at the blockchain latest height (Expects blocks are consecutive (can not skip blocks))
• lru of blocks disabled.
• Added metric that checks max estimated block time