[#13324] Migrate InstructorCoursesPage to SQL-based version

[WeeJean]

Part of #13324

Description

This PR creates the SQL-based PageObject for the InstructorCoursesPage to support the ongoing migration to the SQL backend.

I have implemented InstructorCoursesPageSql.java, mirroring the logic of the existing InstructorCoursesPage.java but adapted to interact with SQL entities.

Changes

• Created: InstructorCoursesPageSql in teammates.e2e.pageobjects.
• Entity Migration: Updated methods to accept teammates.storage.sqlentity.Course instead of CourseAttributes.
• ID Handling: Used course.getId() as the SQL entity retains the String-based ID as the primary key.
• Test Library: Updated assertions to use JUnit 5 (org.junit.jupiter.api.Assertions) to align with modern project standards.

Verification

• Verified syntax and imports by running ./gradlew compileTestJava.
• Manually verified that logic (e.g. iterating through lists, checking table values) matches the original InstructorCoursesPage.java implementation.