feat(backend): integrate action handlers, turn timer, round manger, and ready system together

[mlevi15]

Proposed Changes

• Adds an onEnd method to the turn timer service so that we can end a player's timer at the end of a round without starting the next player's timer right away
• Integrates the turn timer with the round manager
• Adds unit tests for the round manager and fixes several issues found in the process
• Updates the turn timer consumer to auto check or fold for the player when their time is up
• Updates the ready system consumer to start the round once everyone has readied up

Linked Issue

resolves #142 resolves #144

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Merge Checklist

• [x] My code follows the code style of this project.
• [x] All new and existing tests passed.
• [x] Any dependent changes have been merged in downstream modules.
• [x] I have provided inline technical documentation (tsdocs) where necessary.
• [x] My change requires a change to the root documentation.
• [x] I have updated the documentation accordingly.