Added Splay Trees in DSA section

[kosuri-indu]

PR Description

Added content related to splay-trees under the ds-algorithms section. Kindly let me know if more content is required.

Related Issues

• Closes Add Content: Splay Trees in DS-Algorithms section #1053

Checklist

• I have gone through the contributing guide
• I have updated my branch and synced it with project main branch before making this PR

Undertaking

I declare that:

1. The content I am submitting is original and has not been plagiarized.
2. No portion of the work has been copied from any other source without proper attribution.
3. The work has been checked for plagiarism, and I assure its authenticity.

I understand that any violation of this undertaking may have legal consequences that I will bear and could result in the withdrawal of any recognition associated with the work.

• I Agree

[kosuri-indu]

@ashitaprasad @animator
Please review this PR, worked on this since morning, kindly assign respective level :)
Thank you.