Starting code for c++ backend of trees

[Kishan-Ved]

References to other Issues or PRs or Relevant literature

Starting code for #550. This is more like a template.

Brief description of what is fixed or changed

This is some starting code for the trees backend. Honestly, some of this was written by ChatGPT, although I have understood and ensured that most of it is correct and necessary. Please check this and let me know if it is correct, so I can proceed with this. Also, please let me know what part has to be included in header file etc.

[Kishan-Ved]

This might not seem like a lot of code addition, but I prefer making small PRs and getting code verified atleast at the start.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.552%. Comparing base (ec0b015) to head (cf62fc5). Report is 1 commits behind head on main.

:exclamation: Current head cf62fc5 differs from pull request most recent head 8ec0296. Consider uploading reports for the commit 8ec0296 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #551 +/- ## ========================================= Coverage 97.552% 97.552% ========================================= Files 34 34 Lines 4331 4331 ========================================= Hits 4225 4225 Misses 106 106 ``` [](https://app.codecov.io/gh/codezonediitj/pydatastructs/pull/551?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=codezonediitj)

[Kishan-Ved]

Gentle Reminder, please check this.

[czgdp1807]

Looks duplicate of #555. Closing this in favour of #555.