Add scroll to highlighted lines

[fabricionaweb]

This is related to issue #175 but I also did some more work, sorry I couldnt resist 😇

• changed a little the getSelectedLines:
  location.hash will always return string so no need the optional channing
• changed a little the highlightLines:
  getSelectedLines will always return array and already check the location.hash before so I replaced that if and add some deconstruct assignment, just small changes to reduce some lines
• changed the setAttribute/removeAttribute for toggleAttribute with force parameter, just small change to reduce some lines
• added a new method scrollToLine to scroll to the highlighted lines
  it unfortunatelly "needs" the setTimeout in order to always get fired, otherwise it will only works for a new page load (not for refresh). It does works better having it.
• added a new block inside watchForShiftClick to disable native click on go to top to prevent it to remove the currently highlighted lines
• removed async/await from DOMContentLoaded as it is not needed

[robherley]

Overall looks good 👍 one tiny question

[robherley]

Is there a specific reason why you removed the await? It's an async function, and in the mermaid docs examples it's awaited: https://mermaid.js.org/config/usage.html#using-mermaid-run

[robherley]

eh, it's fine as-is. i'll merge and sneak this into the latest release