Removed external library and added clustering algorithm

[amandelpie]

Description

The idea behind this PR is replacement of the clustering algorithm from the external library on the our own implementation to reduce the size of jar

Fixes #345

Type of Change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Automated Testing

All utbot-summaries tests should generate the same results

Checklist (remove irrelevant options):

• The change followed the style guidelines of the UTBot project
• Self-review of the code is passed
• The change contains enough commentaries, particularly in hard-to-understand areas
• New documentation is provided or existed one is altered
• No new warnings
• Tests that prove my change is effective
• All tests pass locally with my changes

[onewhl]

Looks good to me!