[iOS] Upgrade button on Course Home

[moiz994]

We need to add a button on the course home/dashboard screen for learners to be able to upgrade their courses.

The following image is of the current implementation of this button on the product app:

⚠️ With the release of FC-0047 the course resume button is taking up the primary button. We need to move towards a configurable approach where upgrade can be primary.

Acceptance criteria:

• The button is distinguishable on screen that it leads to course upgrade
• Tapping the button opens the value prop modal