Scan: Implemented Delegators and ProposedBlock tabs

[pzshine]

Fixed: #2438

Implementation details

• Implemented tabs for Validator index page
  • Delegators tab
  • ProposedBlock tab

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[render]

Your Render PR Server URL is https://d3n-scan-pr-2500.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-bsulsioti7jbdtbejpr0.

[evilpeach]

1. We don't display the proposed block count for now because it will make a lot of load on database. So, let's remove it.
2. Remove the pagination on the proposed blocks for both (Desktop and Mobile).