[BCNM] Implement BCNM20 Shooting Fish

[The-Aerec]

I affirm:

• [x] I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• [x] I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• [x] I have read and understood the Contributing Guide and the Code of Conduct.
• [x] I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

Implements the Aqua Ball Mechanic for BCNM20 shooting fish.

Basis and evidence for following changes: https://youtu.be/V0Qp99O1AkA https://drive.google.com/open?id=1ZpZ9FEQ3TYeCc9lPig-y2p6pCRLNkdyF https://ffxiclopedia.fandom.com/wiki/Shooting_Fish

Ability 313 it is - renamed from counterspore for clarity

Steps to test these changes

Enter BCNM20 shooting fish and see the mobs properly only use their knockback aquaball as a auto-attack.