moved atomic planner into main repo from stockpile

[mkultraWasHere]

Description

Moving atomic planner to main repo (as a requirement for operations).

*There is a corresponding PR in the stockpile plugin for this planner location change. -> mitre/stockpile#565

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

[sonarqubecloud]

Please retry analysis of this Pull-Request directly on SonarCloud.

[mkultraWasHere]

@clenk Take another look

[clenk]

Should we check the order of the links in test_atomic_0?

Also would be good to give the tests more descriptive names, like test_no_links instead of test_atomic_1

[mkultraWasHere]

^ @djlawren (if you have time to handle today)

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

96.7% Coverage
0.0% Duplication