Refactored LoadBalancing into an interface #92

Job	Run time
Format / pre-commit	32s
Format / Links	18s
Integration / Dummy	1m 19s
PIP / Install	1m 6s
Build Cache / OpenMPI 5	41s
Domain Decomp / Unit	1m 5s
Adaptivity Serial / Unit & Integration	1m 3s
Adaptivity Parallel / Integration	47s
User-Side / Unit	47s
Adaptivity Parallel / Unit	47s
Coverage / Evaluate	48s
	9m 13s

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