non-equi join rewrite numba

[samukweku]

PR Description

Please describe the changes proposed in the pull request:

• reimplementation of the algorithm that powers the non-equi join in numba
• more info in the docs regarding range joins, and where numba can be helpful
• improved performance for numba for range joins and multiple non equi joins when getting first/last match

This PR improves conditional_join.

PR Checklist

Please ensure that you have done the following:

1. [x] PR in from a fork off your branch. Do not PR from <your_username>:dev, but rather from <your_username>:<feature-branch_name>.
2. [x] If you're not on the contributors list, add yourself to AUTHORS.md.
3. [x] Add a line to CHANGELOG.md under the latest version header (i.e. the one that is "on deck") describing the contribution.
   • Do use some discretion here; if there are multiple PRs that are related, keep them in a single line.

Automatic checks

There will be automatic checks run on the PR. These include:

• Building a preview of the docs on Netlify
• Automatically linting the code
• Making sure the code is documented
• Making sure that all tests are passed
• Making sure that code coverage doesn't go down.

Relevant Reviewers

Please tag maintainers to review.

• @ericmjl

[ericmjl]

🚀 Deployed on https://deploy-preview-1341--pyjanitor.netlify.app

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 96.44269% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 95.87%. Comparing base (62c57c6) to head (d7aafb9). Report is 10 commits behind head on dev.

:exclamation: Current head d7aafb9 differs from pull request most recent head 4fca4c0

Please upload reports for the commit 4fca4c0 to get more accurate results.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #1341 +/- ## ========================================== + Coverage 94.48% 95.87% +1.39% ========================================== Files 80 80 Lines 4367 4197 -170 ========================================== - Hits 4126 4024 -102 + Misses 241 173 -68 ```

[ericmjl]

@samukweku is this one ready for review? On GitHub it looks like it's still being marked as a draft.

[samukweku]

@ericmjl not yet, still got some optimisations that I am hopeful to pull off

[samukweku]

@ericmjl not familiar with the jitter function. can i get your help with the failing test function. thanks

[ericmjl]

@ericmjl not familiar with the jitter function. can i get your help with the failing test function. thanks

Not a problem, @samukweku. I encountered a similar issue when testing locally so I decided to make the test a bit more lenient.

[ericmjl]

@samukweku, apologies for the long turnaround time here. I think we should merge this in, as (a) the PR has been open for a long time, and (b) I've already committed to the branch. Once the CI checks are done, I'll do a merge!

[ericmjl]

@samukweku I have merged! Thank you for taking care of pyjanitor, I really appreciate it!