Add multi-line suggestion migrations
Adds outdated, lines_above and lines_below columns to suggestions table. outdated - boolean which represents whether the suggestion is outdated or not. For instance, if any line changed after you left the multi-line suggestion, even though the note is not outdated, it helps tracking if the content has changed in the latest file. We cache this information in a column given it's not a cheap operation to do for every suggestion in the request time. lines_below, lines_above - persists the parsed arguments from `suggestion:-10+3` syntax, where `10` would be lines_above and 3 lines_below. We need that to dynamically calculate which lines we should monitor for outdating / persisting the correct content in from_content column.