Create bookmarks using query parameters

[tobisupreme]

This PR...

Changes

• Bookmarks no longer have a title
• Bookmarks are created using query parameters i.e

POST /bookmarks?postId=id-of-content-to-bookmark&postType=postType
where postType is one of 'Answer', 'Comment', 'Post', or 'Question'

• To delete multiple bookmarks at a go, send a DELETE request to
  /bookmarks/bulk-delete. It's payload is an object with a property of bookmarkIds. The value is an array with at least one bookmarkId

  {
    "bookmarkIds": ["bookmarkId1", "bookmarkId2", "bookmarkId3"]
  }

Checklist

• tested locally
• added new dependencies
• updated the Swagger API docs
• updated the Postman collection
• added a test
• linter passes
• format check passes

Fixes #227

[Boye95]

Thanks @tobisupreme