[FEATURE] [NG23-176] Set course welcome title and encouraging subtitle as author and instructor

[gastonabella]

NG23-176

Changes introduced:

• Add new welcome_title and encouraging_subtitle fields to the projects and sections table.
• Allow setting and editing these fields as a project or product author and as a section instructor.
• Display both the Welcome Title and Encouraging Subtitle on the student's homepage.

Scenario 1: Set the Welcome Title and Encouraging Subtitle as a project's author and create a section that inherits these fields.

https://github.com/Simon-Initiative/oli-torus/assets/26532202/03146ab4-fdc3-4268-92cd-6c41dd8213d9

Scenario 2: Set the Welcome Title and Encouraging Subtitle as a product's author and create a section that inherits these fields.

https://github.com/Simon-Initiative/oli-torus/assets/26532202/7c63ed4e-fcc9-4155-b95d-2b6dfca3372c

Scenario 3: Set the Welcome Title and Encouraging Subtitle as a section's instructor and see these fields when visiting the course homepage as a student.

https://github.com/Simon-Initiative/oli-torus/assets/26532202/995a1126-833a-4d00-bd4e-35bdb6c2551f

[gastonabella]

@darrensiegel this is ready for review again. Let me know if something else needs to be changed 🙌