feat(footer): enhance newsletter and add socials link

[dev129]

Footer UI & space optimization

This code contains the Footer UI and space reduction.

Closes: #877

Footer UI and space reduction

The following has been done in the Issue

• There has been addition of social links
• An option to subscribe to Newsletter
• Three separate columns - Students, Mentors, Legal
• Logo of Grabtern with the tagline below.
• Twitter icon updated to X icon.

Checklist:

• My code follows the style guidelines of this project.
• My code adheres to the established style guidelines of this project.
• I have conducted a self-review of my code.
• I have included comments in areas that may be difficult to understand.
• I have made corresponding updates to the project documentation.
• My changes have not introduced any new warnings.

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[aslams2020]

This PR has been merged by the GSSoC team
here - sanjay-kv/Open-source-Practice#1413

Don't add labels to it now.
You'll get the points in the leaderboard update.