Create function that implements Daily task of executing trades

[JAYKAY2291]

Summary

Add function that executes trades made by student accounts. The trades will be seen as "pending" by student user and not "completed" until the end of the day when all trades will be finalized.

Things out of Scope

Adding API is not part of this issue.

Things to Consider

Stock is bought at the price at the the time of trade and API change should not be taken into account.

Criteria for Completion

• When a Student purchases stock, it will initiate a trade.
• Trade will be listed as "pending" until end of day.
• At end of day, "pending" trade will convert to "completed trade."
• This feature should only be available to student users.
• Add an automated test proving that it works