Teacher Assignments: File Upload button/ accordion collapse+ expand

[mygurukool]

As a teacher, i upload the files from edit assignment screen, therefore upload button next to the exercise material should not be visible for teacher (but visible only for student)

Accordion collapse + expand has no functionality unlike for student, therefore the arrow buttons can only confuse teacher

[harshmewada]

https://github.com/mygurukool/schoolUI/commit/c1f0850ddc8b83d48996f37c90c8f2cd4268a246

[mygurukool]

impl