feat: Make request tab sections collapsible with visual hierarchy

[Nihal-Kumar]

• Adds collapsible sections for request tab headers like General, Request Headers, Query Parameters, etc.
• Introduces showing header count when header collapsed.
• Improves visual hierarchy of key-value pairs by styling keys with font weight and making the UI closer to Browser Dev Tools
• No new dependencies added.

Updates: https://github.com/user-attachments/assets/67c63608-bd3e-48c8-9f68-19edd7445cfc

Images:

Before:

References: #35214