feat: Add btree with insertion, deletion, and search

[caojoshua]

see https://en.wikipedia.org/wiki/B-tree

[caojoshua]

Could I get a review for this?

[github-actions]

This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[caojoshua]

Ping to prevent PR from auto closing. Would still like reviews.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 92.11618% with 19 lines in your changes are missing coverage. Please review.

Project coverage is 86.58%. Comparing base (3f2fa29) to head (3db04ee).

Files	Patch %	Lines
structure/tree/btree.go	92.11%	10 Missing and 9 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #703      +/-   ##
==========================================
+ Coverage   86.33%   86.58%   +0.24%     
==========================================
  Files         195      196       +1     
  Lines        6242     6483     +241     
==========================================
+ Hits         5389     5613     +224     
- Misses        721      730       +9     
- Partials      132      140       +8     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[caojoshua]

Code coverage helped me find bugs where root is null after deleting everything. Added a testcase to handle this case. This should also help with line coverage, but I'm not sure how to check that locally.

[raklaptudirm]

Seems you haven't formatted some of the changed files, please do so.