Add profile page fields to player table

[jaeheonshim]

Update the Player entity to include the fields for profile page implementation

• Username
• Full name
• Bio/About Me
• School
• Major
• Member since
• Links to socials

For now, let's accept only a predefined set of links to socials (e.g. GitHub, LinkedIn, Personal website). So don't create a new table for social links and instead create a nullable column for each link (e.g. github_link, linkedin_link, website_link)

Acceptance criteria:

• Updated DBML schema with new fields added to Player table
• Flyway schema migration file that keeps database in parity with DBML schema
• Updated entity class in codebase with new fields

No new dto classes for now, until we need to create endpoints.
Don't worry about avatars.