Terminal State not saved when leaving current assigment

[S-Schickentanz]

When changing between assignments (or in general when you exit the current assignment or even reload the page) the terminalStatus is reset / not persistent.
This leads to data loss when the user (accidentally) navigates to other resources.

To reproduce:

• Start assignment
• Write something in the terminal
• Reload Page / Go to "Assignment Overview" and resume the assignment
• The last terminalState should now be inaccessible

Possible solution:
Serialize data and temporarily save it in localStorage