Implemented black swan

What has been done in this MR?

• Implements #300 (closed) (which I'm not even sure should be implemented)

Unlike any other MR I also want to know what you think of this addition. "It's not authentic and should not be implemented" is a fine response.

What should testers check?

• The black swan is at the 2 separate points in Falador
• The black swans are examine-able
• The black swans are swimming

I'm not sure why but these 2 swans don't swim even with walk set to true. For me this is a bit of an argument against this implementation but I wanted to get some other thoughts.

Fixed that issue

• I have tested these changes thoroughly.

• I used the relevant Zaros tool for any JSON edits where possible, and have attached screenshots of any changes.