feat: new api for compaction

[dkharms]

Description

In this PR I've implemented all necessary API for compaction. And also changed visibility of all methods inside fracmanager package since they should not be exported.

I expect that there will be slight tweaks and changes to this API (e.g. method signature change) but the whole idea will be the same.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 53.90071% with 65 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.59%. Comparing base (8fb9752) to head (d657428).

Files with missing lines	Patch %	Lines
fracmanager/fraction_registry.go	54.63%	42 Missing and 2 partials ⚠️
fracmanager/fracmanager.go	24.00%	18 Missing and 1 partial ⚠️
fracmanager/lifecycle_manager.go	80.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #429      +/-   ##
==========================================
- Coverage   70.82%   70.59%   -0.24%     
==========================================
  Files         225      225              
  Lines       17504    17566      +62     
==========================================
+ Hits        12398    12400       +2     
- Misses       4182     4242      +60     
  Partials      924      924              

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[github-actions]

🔴 Performance Degradation

Some benchmarks have degraded compared to the previous run.
Click on Show table button to see full list of degraded benchmarks.

Show table

Name	Previous	Current	Ratio	Verdict
AggWide/size=1000000-4	8fb975	2ef516
	469.00 B/op	553.00 B/op	1.18	🔴