Upgrade Material UI and other UI Components

[RachitKeertiDas]

Material UI has released v5 since quite some time now. The project is currently using v4. We should check and upgrade if feasible.

Here's a small bucket list of what needs to be done:

• Figure out breaking changes
• Check default style changes
• Check for deprecated components that we use and their replacements
• Find out steps for migration
• Actually do the migration
• Look for regressions and fix them

[RachitKeertiDas]

This is not just UI related stuff, other libraries such as Firebase, React Router etc also need updating.
Should probably handle it in a different issue though.