[Android] Full screen loader whille course is upgarding

[moiz994]

While implementing IAP on the legacy apps, it was seen that after processing the payments it takes some time for the course to upgrade. Considering design heuristics and for a more interactive approach, we have implemented a full-screen loader to show while the learners wait for their course to be upgraded.

Acceptance criteria:

• The loader shows up after the payment is processed and the backend is unlocking the course content
• The loader is not shown when upgrading is completed
• The loader illustration should either be generic or should go with the theme of the app

Current implementation:
Video Demo

[moiz994]

@farhan-arshad-dev @k1rill we need to update the rocket illustration to the following rocket icon in order to match the schema design system.



https://fonts.google.com/icons?selected=Material+Symbols+Outlined:rocket_launch:FILL@0;wght@400;GRAD@0;opsz@24&icon.query=rocket&icon.size=24&icon.color=%235f6368

[moiz994]

@farhan-arshad-dev @k1rill please have a look at the above loading screen and let me know if there are any questions.