New plugin: Readwise

@arminta @shabegom Yes, it’s a restriction is there for 2 main reasons:

  • Allowing download of all existing highlights could trigger rate limiting of the Readwise API and I haven’t implemented support for that yet (it requires more logic in terms of retrying requests, pagination, etc)
  • If you already have many highlights and for whatever reason don’t have the id stored as highlight_id: <id> it would insert highlights again, leading to a potential mess in your vault