Make Pinned courses rearrangable

[abhitrueprogrammer]

Is your feature request related to a problem? Please describe.
Would be useful to reorder pinned courses. Moreover user would expect this feature and would be really annoyed if it isn't the case

Describe the solution you'd like
Use the library used in upload page maybe?

Additional context
The pages that need to be changed:

[Abh1noob]

additionally, in pin subject modal, when we press enter, the highlighted course in dropdown should be selected and added

currently, we have to rely completely on mouse

(just a QoL change)