feat: update extension settings layout

[amitamrutiya]

Describe the changes you have made in this PR

I have implemented the recommended changes mentioned in the issue. In this PR I make sure that:

• Page tile contains a description "Global settings that affect your experience on all connected wallets in - Alby Extension.". Space between title and descriptions should be 4px.
• Section headers are text-xl/bold
• All buttons and dropdowns should have fixed 256px width
• Use Title case in all list item labels and buttons
• Delete Nostr section
• Delete legacy section

Link this PR to an issue [optional]

2874

Fixes #2874

Type of change

• fix: remove legacy section from extension setting screen
• fix: use title case in extension setting screen
• feat: add extension setting subtitle and general section title

Screenshots of the changes [optional]

Checklist

• [X] Self-review of changed code
• [X] Manual testing
• [X] Added automated tests where applicable
• [X] Update Docs & Guides
• For UI-related changes
• [X] Darkmode
• [X] Responsive layout

[stackingsaunter]

Hey @amitamrutiya2210 are you still working on this one?

[amitamrutiya]

From my side, the work is done. So, this PR is ready for review.

[stackingsaunter]

@amitamrutiya2210 I see thanks 🙏🙏

[pavanjoshi914]

Thanks for the pr! fixed some layout issues and styles and code conventions. @reneaaron let me know if want some additional changes!

TODO: update wallet settings this focus only on extension settings

[pavanjoshi914]

Rest LGTM!

[pavanjoshi914]

regarding outdated translations warnings. i don't think we shall remove it. it's just that strings were capitalised in English version

[pavanjoshi914]

tAck