Updated prereq warning to direct users to Transfer Credits menu

[KevinWu098]

Description

1. Updated prereq/warning message:

      Prerequisite(s) not met! Missing: {requiredCourses?.join(', ')} 
      <br />
      Already completed prerequisite(s)? Click 'Transfer Credits' at the top of the planner to clear the prerequisite(s).

Screenshots

Before:

After:

Steps to verify/test this change:

• Verify changes work as expected on staging instance

Final Checks:

• Verify successful deployment
• Delete branch

(optional)

• Write tests
• Write documentation

Closes #302

[js0mmer]

LGTM. On second thought though, we might want to specify that this is only for transferring credit from another school.

[github-actions]

Deployed staging instance to https://staging-339.peterportal.org