Implement new FanGraphs Leaderboard API

[ss77995ss]

Description

• FanGraphs update their leaderboard page in 2023. Therefore the old data scraping does not work. Currently, we use their legacy url https://www.fangraphs.com/leaders-legacy.aspx now. But the legacy one might not update after 2023.
  • ref: https://blogs.fangraphs.com/weve-updated-our-major-league-leaderboards-interface/
  • related issue: Fangraphs functions fail to scrape data, returns empty DF after site update #376
• To use latest leaderboard, apply fangraph's leaderboard api to get the data
  • url: link
  • commit: 0f39311
• Add a legacy flag to remain obtaining data from legacy leaderboard. Also add a notification in document
  • commit: 7205275, ec9e2bc

Need Discussions

• Currently all the params seem to work but I am not check completely. Might need more testing.
• Test will not pass since the response data is different between legacy and latest leaderboard. Need some help for the testing data
• Look like issue: MILB SCRAPE FROM NEW FANGRAPHS DATABASE #396 can also be fixed if we use fangraphs api link

TODO

• Fix testing
• Delete demo commit