Rewrite and split of actions.ts file

[hburn7]

Reference: https://nextjs.org/blog/security-nextjs-server-components-actions
Server-side actions should be split up into files and organized to improve clarity and code quality. As of now they all live in a single file.

Tasks (Split all of the following):

• Login / logout
• Session management
• Cookies
• Users
• Players
• Tournaments