Gh-3274: Simplified federation proof of concept

[tb06904]

This is a basic proof of concept to demonstrate a simpler federated store with a rethink on how merging works and the required classes.

This is not feature complete, the idea is this serves as a base for some additional required features. Once feature complete this may be able to replace the existing federated store to address its issues and technical debt.

Features present:

• Extendable merge/aggregator classes that support partially lazy element aggregation based on schemas.
• Ability to add graphs via the stores java methods.
• Operation handler for delegation to sub graphs (both for operations with and without output).
• Basic federated handler for merging schemas.
• Limited unit and integration testing.
• Ability to pass graph IDs and a toggle for element aggregation via operation options.

[codecov]

Codecov Report

Attention: Patch coverage is 73.82550% with 39 lines in your changes missing coverage. Please review.

Project coverage is 67.59%. Comparing base (cd93f5e) to head (03467ff).
Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
...v/gchq/gaffer/federated/simple/FederatedStore.java	70.45%	11 Missing and 2 partials ⚠️
...imple/merge/operator/ElementAggregateOperator.java	71.42%	4 Missing and 4 partials ⚠️
...e/operation/handler/FederatedOperationHandler.java	61.90%	7 Missing and 1 partial ⚠️
...derated/simple/merge/DefaultResultAccumulator.java	63.15%	3 Missing and 4 partials ⚠️
...ted/simple/operation/handler/GetSchemaHandler.java	81.81%	1 Missing and 1 partial ⚠️
...mple/operation/handler/FederatedOutputHandler.java	93.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #3275      +/-   ##
=============================================
+ Coverage      67.55%   67.59%   +0.03%     
  Complexity      2595     2595              
=============================================
  Files            929      936       +7     
  Lines          29824    29973     +149     
  Branches        3291     3318      +27     
=============================================
+ Hits           20149    20259     +110     
- Misses          8225     8251      +26     
- Partials        1450     1463      +13     

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[p29876]

LGTM 🔥
Only a couple nitpicks but this is just a PoC so can be left for now if you want

[sonarcloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud