feat: add implementations of `CheckInit` and `OverrideInit` #421

Job	Run time
Tests (1, Core) / Tests - Core	9m 15s
Tests (1, Downstream) / Tests - Downstream	34m 26s
Tests (1, Python) / Tests - Python	16m 28s
Tests (1, QA) / Tests - QA	8m 50s
Tests (lts, Core) / Tests - Core	8m 53s
Tests (lts, Downstream) / Tests - Downstream	29m 17s
Tests (lts, Python) / Tests - Python	10m 13s
Tests (lts, QA) / Tests - QA	6m 31s
Tests (pre, Core) / Tests - Core	4m 12s
Tests (pre, Downstream) / Tests - Downstream	29m 54s
Tests (pre, Python) / Tests - Python	10m 44s
Tests (pre, QA) / Tests - QA	1m 10s
	2h 49m 53s

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